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1# Select 32 or 64 bit
2config 64BIT
3 bool "64-bit kernel" if ARCH = "x86"
4 default ARCH = "x86_64"
5 ---help---
6 Say yes to build a 64-bit kernel - formerly known as x86_64
7 Say no to build a 32-bit kernel - formerly known as i386
8
9config X86_32
10 def_bool !64BIT
11 select CLKSRC_I8253
12
13config X86_64
14 def_bool 64BIT
15 select X86_DEV_DMA_OPS
16
17### Arch settings
18config X86
19 def_bool y
20 select HAVE_AOUT if X86_32
21 select HAVE_UNSTABLE_SCHED_CLOCK
22 select HAVE_IDE
23 select HAVE_OPROFILE
24 select HAVE_PCSPKR_PLATFORM
25 select HAVE_PERF_EVENTS
26 select HAVE_IRQ_WORK
27 select HAVE_IOREMAP_PROT
28 select HAVE_KPROBES
29 select HAVE_MEMBLOCK
30 select HAVE_MEMBLOCK_NODE_MAP
31 select ARCH_DISCARD_MEMBLOCK
32 select ARCH_WANT_OPTIONAL_GPIOLIB
33 select ARCH_WANT_FRAME_POINTERS
34 select HAVE_DMA_ATTRS
35 select HAVE_DMA_CONTIGUOUS if !SWIOTLB
36 select HAVE_KRETPROBES
37 select HAVE_OPTPROBES
38 select HAVE_FTRACE_MCOUNT_RECORD
39 select HAVE_C_RECORDMCOUNT
40 select HAVE_DYNAMIC_FTRACE
41 select HAVE_FUNCTION_TRACER
42 select HAVE_FUNCTION_GRAPH_TRACER
43 select HAVE_FUNCTION_GRAPH_FP_TEST
44 select HAVE_FUNCTION_TRACE_MCOUNT_TEST
45 select HAVE_SYSCALL_TRACEPOINTS
46 select HAVE_KVM
47 select HAVE_ARCH_KGDB
48 select HAVE_ARCH_TRACEHOOK
49 select HAVE_GENERIC_DMA_COHERENT if X86_32
50 select HAVE_EFFICIENT_UNALIGNED_ACCESS
51 select USER_STACKTRACE_SUPPORT
52 select HAVE_REGS_AND_STACK_ACCESS_API
53 select HAVE_DMA_API_DEBUG
54 select HAVE_KERNEL_GZIP
55 select HAVE_KERNEL_BZIP2
56 select HAVE_KERNEL_LZMA
57 select HAVE_KERNEL_XZ
58 select HAVE_KERNEL_LZO
59 select HAVE_HW_BREAKPOINT
60 select HAVE_MIXED_BREAKPOINTS_REGS
61 select PERF_EVENTS
62 select HAVE_PERF_EVENTS_NMI
63 select ANON_INODES
64 select HAVE_ALIGNED_STRUCT_PAGE if SLUB && !M386
65 select HAVE_CMPXCHG_LOCAL if !M386
66 select HAVE_CMPXCHG_DOUBLE
67 select HAVE_ARCH_KMEMCHECK
68 select HAVE_USER_RETURN_NOTIFIER
69 select ARCH_BINFMT_ELF_RANDOMIZE_PIE
70 select HAVE_ARCH_JUMP_LABEL
71 select HAVE_TEXT_POKE_SMP
72 select HAVE_GENERIC_HARDIRQS
73 select SPARSE_IRQ
74 select GENERIC_FIND_FIRST_BIT
75 select GENERIC_IRQ_PROBE
76 select GENERIC_PENDING_IRQ if SMP
77 select GENERIC_IRQ_SHOW
78 select GENERIC_CLOCKEVENTS_MIN_ADJUST
79 select IRQ_FORCED_THREADING
80 select USE_GENERIC_SMP_HELPERS if SMP
81 select HAVE_BPF_JIT if X86_64
82 select CLKEVT_I8253
83 select ARCH_HAVE_NMI_SAFE_CMPXCHG
84 select GENERIC_IOMAP
85 select DCACHE_WORD_ACCESS
86 select GENERIC_SMP_IDLE_THREAD
87 select HAVE_ARCH_SECCOMP_FILTER
88 select BUILDTIME_EXTABLE_SORT
89 select GENERIC_CMOS_UPDATE
90 select CLOCKSOURCE_WATCHDOG
91 select GENERIC_CLOCKEVENTS
92 select ARCH_CLOCKSOURCE_DATA if X86_64
93 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
94 select GENERIC_TIME_VSYSCALL if X86_64
95 select KTIME_SCALAR if X86_32
96 select GENERIC_STRNCPY_FROM_USER
97 select GENERIC_STRNLEN_USER
98
99config INSTRUCTION_DECODER
100 def_bool (KPROBES || PERF_EVENTS || UPROBES)
101
102config OUTPUT_FORMAT
103 string
104 default "elf32-i386" if X86_32
105 default "elf64-x86-64" if X86_64
106
107config ARCH_DEFCONFIG
108 string
109 default "arch/x86/configs/i386_defconfig" if X86_32
110 default "arch/x86/configs/x86_64_defconfig" if X86_64
111
112config LOCKDEP_SUPPORT
113 def_bool y
114
115config STACKTRACE_SUPPORT
116 def_bool y
117
118config HAVE_LATENCYTOP_SUPPORT
119 def_bool y
120
121config MMU
122 def_bool y
123
124config SBUS
125 bool
126
127config NEED_DMA_MAP_STATE
128 def_bool (X86_64 || INTEL_IOMMU || DMA_API_DEBUG)
129
130config NEED_SG_DMA_LENGTH
131 def_bool y
132
133config GENERIC_ISA_DMA
134 def_bool ISA_DMA_API
135
136config GENERIC_BUG
137 def_bool y
138 depends on BUG
139 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
140
141config GENERIC_BUG_RELATIVE_POINTERS
142 bool
143
144config GENERIC_HWEIGHT
145 def_bool y
146
147config GENERIC_GPIO
148 bool
149
150config ARCH_MAY_HAVE_PC_FDC
151 def_bool ISA_DMA_API
152
153config RWSEM_GENERIC_SPINLOCK
154 def_bool !X86_XADD
155
156config RWSEM_XCHGADD_ALGORITHM
157 def_bool X86_XADD
158
159config GENERIC_CALIBRATE_DELAY
160 def_bool y
161
162config ARCH_HAS_CPU_RELAX
163 def_bool y
164
165config ARCH_HAS_DEFAULT_IDLE
166 def_bool y
167
168config ARCH_HAS_CACHE_LINE_SIZE
169 def_bool y
170
171config ARCH_HAS_CPU_AUTOPROBE
172 def_bool y
173
174config HAVE_SETUP_PER_CPU_AREA
175 def_bool y
176
177config NEED_PER_CPU_EMBED_FIRST_CHUNK
178 def_bool y
179
180config NEED_PER_CPU_PAGE_FIRST_CHUNK
181 def_bool y
182
183config ARCH_HIBERNATION_POSSIBLE
184 def_bool y
185
186config ARCH_SUSPEND_POSSIBLE
187 def_bool y
188
189config ZONE_DMA32
190 bool
191 default X86_64
192
193config AUDIT_ARCH
194 bool
195 default X86_64
196
197config ARCH_SUPPORTS_OPTIMIZED_INLINING
198 def_bool y
199
200config ARCH_SUPPORTS_DEBUG_PAGEALLOC
201 def_bool y
202
203config HAVE_INTEL_TXT
204 def_bool y
205 depends on EXPERIMENTAL && INTEL_IOMMU && ACPI
206
207config X86_32_SMP
208 def_bool y
209 depends on X86_32 && SMP
210
211config X86_64_SMP
212 def_bool y
213 depends on X86_64 && SMP
214
215config X86_HT
216 def_bool y
217 depends on SMP
218
219config X86_32_LAZY_GS
220 def_bool y
221 depends on X86_32 && !CC_STACKPROTECTOR
222
223config ARCH_HWEIGHT_CFLAGS
224 string
225 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
226 default "-fcall-saved-rdi -fcall-saved-rsi -fcall-saved-rdx -fcall-saved-rcx -fcall-saved-r8 -fcall-saved-r9 -fcall-saved-r10 -fcall-saved-r11" if X86_64
227
228config ARCH_CPU_PROBE_RELEASE
229 def_bool y
230 depends on HOTPLUG_CPU
231
232config ARCH_SUPPORTS_UPROBES
233 def_bool y
234
235source "init/Kconfig"
236source "kernel/Kconfig.freezer"
237
238menu "Processor type and features"
239
240config ZONE_DMA
241 bool "DMA memory allocation support" if EXPERT
242 default y
243 help
244 DMA memory allocation support allows devices with less than 32-bit
245 addressing to allocate within the first 16MB of address space.
246 Disable if no such devices will be used.
247
248 If unsure, say Y.
249
250config SMP
251 bool "Symmetric multi-processing support"
252 ---help---
253 This enables support for systems with more than one CPU. If you have
254 a system with only one CPU, like most personal computers, say N. If
255 you have a system with more than one CPU, say Y.
256
257 If you say N here, the kernel will run on single and multiprocessor
258 machines, but will use only one CPU of a multiprocessor machine. If
259 you say Y here, the kernel will run on many, but not all,
260 singleprocessor machines. On a singleprocessor machine, the kernel
261 will run faster if you say N here.
262
263 Note that if you say Y here and choose architecture "586" or
264 "Pentium" under "Processor family", the kernel will not work on 486
265 architectures. Similarly, multiprocessor kernels for the "PPro"
266 architecture may not work on all Pentium based boards.
267
268 People using multiprocessor machines who say Y here should also say
269 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
270 Management" code will be disabled if you say Y here.
271
272 See also <file:Documentation/x86/i386/IO-APIC.txt>,
273 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
274 <http://www.tldp.org/docs.html#howto>.
275
276 If you don't know what to do here, say N.
277
278config X86_X2APIC
279 bool "Support x2apic"
280 depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP
281 ---help---
282 This enables x2apic support on CPUs that have this feature.
283
284 This allows 32-bit apic IDs (so it can support very large systems),
285 and accesses the local apic via MSRs not via mmio.
286
287 If you don't know what to do here, say N.
288
289config X86_MPPARSE
290 bool "Enable MPS table" if ACPI
291 default y
292 depends on X86_LOCAL_APIC
293 ---help---
294 For old smp systems that do not have proper acpi support. Newer systems
295 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
296
297config X86_BIGSMP
298 bool "Support for big SMP systems with more than 8 CPUs"
299 depends on X86_32 && SMP
300 ---help---
301 This option is needed for the systems that have more than 8 CPUs
302
303if X86_32
304config X86_EXTENDED_PLATFORM
305 bool "Support for extended (non-PC) x86 platforms"
306 default y
307 ---help---
308 If you disable this option then the kernel will only support
309 standard PC platforms. (which covers the vast majority of
310 systems out there.)
311
312 If you enable this option then you'll be able to select support
313 for the following (non-PC) 32 bit x86 platforms:
314 AMD Elan
315 NUMAQ (IBM/Sequent)
316 RDC R-321x SoC
317 SGI 320/540 (Visual Workstation)
318 STA2X11-based (e.g. Northville)
319 Summit/EXA (IBM x440)
320 Unisys ES7000 IA32 series
321 Moorestown MID devices
322
323 If you have one of these systems, or if you want to build a
324 generic distribution kernel, say Y here - otherwise say N.
325endif
326
327if X86_64
328config X86_EXTENDED_PLATFORM
329 bool "Support for extended (non-PC) x86 platforms"
330 default y
331 ---help---
332 If you disable this option then the kernel will only support
333 standard PC platforms. (which covers the vast majority of
334 systems out there.)
335
336 If you enable this option then you'll be able to select support
337 for the following (non-PC) 64 bit x86 platforms:
338 Numascale NumaChip
339 ScaleMP vSMP
340 SGI Ultraviolet
341
342 If you have one of these systems, or if you want to build a
343 generic distribution kernel, say Y here - otherwise say N.
344endif
345# This is an alphabetically sorted list of 64 bit extended platforms
346# Please maintain the alphabetic order if and when there are additions
347config X86_NUMACHIP
348 bool "Numascale NumaChip"
349 depends on X86_64
350 depends on X86_EXTENDED_PLATFORM
351 depends on NUMA
352 depends on SMP
353 depends on X86_X2APIC
354 ---help---
355 Adds support for Numascale NumaChip large-SMP systems. Needed to
356 enable more than ~168 cores.
357 If you don't have one of these, you should say N here.
358
359config X86_VSMP
360 bool "ScaleMP vSMP"
361 select PARAVIRT_GUEST
362 select PARAVIRT
363 depends on X86_64 && PCI
364 depends on X86_EXTENDED_PLATFORM
365 depends on SMP
366 ---help---
367 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
368 supposed to run on these EM64T-based machines. Only choose this option
369 if you have one of these machines.
370
371config X86_UV
372 bool "SGI Ultraviolet"
373 depends on X86_64
374 depends on X86_EXTENDED_PLATFORM
375 depends on NUMA
376 depends on X86_X2APIC
377 ---help---
378 This option is needed in order to support SGI Ultraviolet systems.
379 If you don't have one of these, you should say N here.
380
381# Following is an alphabetically sorted list of 32 bit extended platforms
382# Please maintain the alphabetic order if and when there are additions
383
384config X86_INTEL_CE
385 bool "CE4100 TV platform"
386 depends on PCI
387 depends on PCI_GODIRECT
388 depends on X86_32
389 depends on X86_EXTENDED_PLATFORM
390 select X86_REBOOTFIXUPS
391 select OF
392 select OF_EARLY_FLATTREE
393 select IRQ_DOMAIN
394 ---help---
395 Select for the Intel CE media processor (CE4100) SOC.
396 This option compiles in support for the CE4100 SOC for settop
397 boxes and media devices.
398
399config X86_WANT_INTEL_MID
400 bool "Intel MID platform support"
401 depends on X86_32
402 depends on X86_EXTENDED_PLATFORM
403 ---help---
404 Select to build a kernel capable of supporting Intel MID platform
405 systems which do not have the PCI legacy interfaces (Moorestown,
406 Medfield). If you are building for a PC class system say N here.
407
408if X86_WANT_INTEL_MID
409
410config X86_INTEL_MID
411 bool
412
413config X86_MDFLD
414 bool "Medfield MID platform"
415 depends on PCI
416 depends on PCI_GOANY
417 depends on X86_IO_APIC
418 select X86_INTEL_MID
419 select SFI
420 select DW_APB_TIMER
421 select APB_TIMER
422 select I2C
423 select SPI
424 select INTEL_SCU_IPC
425 select X86_PLATFORM_DEVICES
426 select MFD_INTEL_MSIC
427 ---help---
428 Medfield is Intel's Low Power Intel Architecture (LPIA) based Moblin
429 Internet Device(MID) platform.
430 Unlike standard x86 PCs, Medfield does not have many legacy devices
431 nor standard legacy replacement devices/features. e.g. Medfield does
432 not contain i8259, i8254, HPET, legacy BIOS, most of the io ports.
433
434endif
435
436config X86_RDC321X
437 bool "RDC R-321x SoC"
438 depends on X86_32
439 depends on X86_EXTENDED_PLATFORM
440 select M486
441 select X86_REBOOTFIXUPS
442 ---help---
443 This option is needed for RDC R-321x system-on-chip, also known
444 as R-8610-(G).
445 If you don't have one of these chips, you should say N here.
446
447config X86_32_NON_STANDARD
448 bool "Support non-standard 32-bit SMP architectures"
449 depends on X86_32 && SMP
450 depends on X86_EXTENDED_PLATFORM
451 ---help---
452 This option compiles in the NUMAQ, Summit, bigsmp, ES7000,
453 STA2X11, default subarchitectures. It is intended for a generic
454 binary kernel. If you select them all, kernel will probe it
455 one by one and will fallback to default.
456
457# Alphabetically sorted list of Non standard 32 bit platforms
458
459config X86_NUMAQ
460 bool "NUMAQ (IBM/Sequent)"
461 depends on X86_32_NON_STANDARD
462 depends on PCI
463 select NUMA
464 select X86_MPPARSE
465 ---help---
466 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
467 NUMA multiquad box. This changes the way that processors are
468 bootstrapped, and uses Clustered Logical APIC addressing mode instead
469 of Flat Logical. You will need a new lynxer.elf file to flash your
470 firmware with - send email to <Martin.Bligh@us.ibm.com>.
471
472config X86_SUPPORTS_MEMORY_FAILURE
473 def_bool y
474 # MCE code calls memory_failure():
475 depends on X86_MCE
476 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
477 depends on !X86_NUMAQ
478 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
479 depends on X86_64 || !SPARSEMEM
480 select ARCH_SUPPORTS_MEMORY_FAILURE
481
482config X86_VISWS
483 bool "SGI 320/540 (Visual Workstation)"
484 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
485 depends on X86_32_NON_STANDARD
486 ---help---
487 The SGI Visual Workstation series is an IA32-based workstation
488 based on SGI systems chips with some legacy PC hardware attached.
489
490 Say Y here to create a kernel to run on the SGI 320 or 540.
491
492 A kernel compiled for the Visual Workstation will run on general
493 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
494
495config STA2X11
496 bool "STA2X11 Companion Chip Support"
497 depends on X86_32_NON_STANDARD && PCI
498 select X86_DEV_DMA_OPS
499 select X86_DMA_REMAP
500 select SWIOTLB
501 select MFD_STA2X11
502 select ARCH_REQUIRE_GPIOLIB
503 default n
504 ---help---
505 This adds support for boards based on the STA2X11 IO-Hub,
506 a.k.a. "ConneXt". The chip is used in place of the standard
507 PC chipset, so all "standard" peripherals are missing. If this
508 option is selected the kernel will still be able to boot on
509 standard PC machines.
510
511config X86_SUMMIT
512 bool "Summit/EXA (IBM x440)"
513 depends on X86_32_NON_STANDARD
514 ---help---
515 This option is needed for IBM systems that use the Summit/EXA chipset.
516 In particular, it is needed for the x440.
517
518config X86_ES7000
519 bool "Unisys ES7000 IA32 series"
520 depends on X86_32_NON_STANDARD && X86_BIGSMP
521 ---help---
522 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
523 supposed to run on an IA32-based Unisys ES7000 system.
524
525config X86_32_IRIS
526 tristate "Eurobraille/Iris poweroff module"
527 depends on X86_32
528 ---help---
529 The Iris machines from EuroBraille do not have APM or ACPI support
530 to shut themselves down properly. A special I/O sequence is
531 needed to do so, which is what this module does at
532 kernel shutdown.
533
534 This is only for Iris machines from EuroBraille.
535
536 If unused, say N.
537
538config SCHED_OMIT_FRAME_POINTER
539 def_bool y
540 prompt "Single-depth WCHAN output"
541 depends on X86
542 ---help---
543 Calculate simpler /proc/<PID>/wchan values. If this option
544 is disabled then wchan values will recurse back to the
545 caller function. This provides more accurate wchan values,
546 at the expense of slightly more scheduling overhead.
547
548 If in doubt, say "Y".
549
550menuconfig PARAVIRT_GUEST
551 bool "Paravirtualized guest support"
552 ---help---
553 Say Y here to get to see options related to running Linux under
554 various hypervisors. This option alone does not add any kernel code.
555
556 If you say N, all options in this submenu will be skipped and disabled.
557
558if PARAVIRT_GUEST
559
560config PARAVIRT_TIME_ACCOUNTING
561 bool "Paravirtual steal time accounting"
562 select PARAVIRT
563 default n
564 ---help---
565 Select this option to enable fine granularity task steal time
566 accounting. Time spent executing other tasks in parallel with
567 the current vCPU is discounted from the vCPU power. To account for
568 that, there can be a small performance impact.
569
570 If in doubt, say N here.
571
572source "arch/x86/xen/Kconfig"
573
574config KVM_CLOCK
575 bool "KVM paravirtualized clock"
576 select PARAVIRT
577 select PARAVIRT_CLOCK
578 ---help---
579 Turning on this option will allow you to run a paravirtualized clock
580 when running over the KVM hypervisor. Instead of relying on a PIT
581 (or probably other) emulation by the underlying device model, the host
582 provides the guest with timing infrastructure such as time of day, and
583 system time
584
585config KVM_GUEST
586 bool "KVM Guest support"
587 select PARAVIRT
588 ---help---
589 This option enables various optimizations for running under the KVM
590 hypervisor.
591
592source "arch/x86/lguest/Kconfig"
593
594config PARAVIRT
595 bool "Enable paravirtualization code"
596 ---help---
597 This changes the kernel so it can modify itself when it is run
598 under a hypervisor, potentially improving performance significantly
599 over full virtualization. However, when run without a hypervisor
600 the kernel is theoretically slower and slightly larger.
601
602config PARAVIRT_SPINLOCKS
603 bool "Paravirtualization layer for spinlocks"
604 depends on PARAVIRT && SMP && EXPERIMENTAL
605 ---help---
606 Paravirtualized spinlocks allow a pvops backend to replace the
607 spinlock implementation with something virtualization-friendly
608 (for example, block the virtual CPU rather than spinning).
609
610 Unfortunately the downside is an up to 5% performance hit on
611 native kernels, with various workloads.
612
613 If you are unsure how to answer this question, answer N.
614
615config PARAVIRT_CLOCK
616 bool
617
618endif
619
620config PARAVIRT_DEBUG
621 bool "paravirt-ops debugging"
622 depends on PARAVIRT && DEBUG_KERNEL
623 ---help---
624 Enable to debug paravirt_ops internals. Specifically, BUG if
625 a paravirt_op is missing when it is called.
626
627config NO_BOOTMEM
628 def_bool y
629
630config MEMTEST
631 bool "Memtest"
632 ---help---
633 This option adds a kernel parameter 'memtest', which allows memtest
634 to be set.
635 memtest=0, mean disabled; -- default
636 memtest=1, mean do 1 test pattern;
637 ...
638 memtest=4, mean do 4 test patterns.
639 If you are unsure how to answer this question, answer N.
640
641config X86_SUMMIT_NUMA
642 def_bool y
643 depends on X86_32 && NUMA && X86_32_NON_STANDARD
644
645config X86_CYCLONE_TIMER
646 def_bool y
647 depends on X86_SUMMIT
648
649source "arch/x86/Kconfig.cpu"
650
651config HPET_TIMER
652 def_bool X86_64
653 prompt "HPET Timer Support" if X86_32
654 ---help---
655 Use the IA-PC HPET (High Precision Event Timer) to manage
656 time in preference to the PIT and RTC, if a HPET is
657 present.
658 HPET is the next generation timer replacing legacy 8254s.
659 The HPET provides a stable time base on SMP
660 systems, unlike the TSC, but it is more expensive to access,
661 as it is off-chip. You can find the HPET spec at
662 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
663
664 You can safely choose Y here. However, HPET will only be
665 activated if the platform and the BIOS support this feature.
666 Otherwise the 8254 will be used for timing services.
667
668 Choose N to continue using the legacy 8254 timer.
669
670config HPET_EMULATE_RTC
671 def_bool y
672 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
673
674config APB_TIMER
675 def_bool y if X86_INTEL_MID
676 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
677 select DW_APB_TIMER
678 depends on X86_INTEL_MID && SFI
679 help
680 APB timer is the replacement for 8254, HPET on X86 MID platforms.
681 The APBT provides a stable time base on SMP
682 systems, unlike the TSC, but it is more expensive to access,
683 as it is off-chip. APB timers are always running regardless of CPU
684 C states, they are used as per CPU clockevent device when possible.
685
686# Mark as expert because too many people got it wrong.
687# The code disables itself when not needed.
688config DMI
689 default y
690 bool "Enable DMI scanning" if EXPERT
691 ---help---
692 Enabled scanning of DMI to identify machine quirks. Say Y
693 here unless you have verified that your setup is not
694 affected by entries in the DMI blacklist. Required by PNP
695 BIOS code.
696
697config GART_IOMMU
698 bool "GART IOMMU support" if EXPERT
699 default y
700 select SWIOTLB
701 depends on X86_64 && PCI && AMD_NB
702 ---help---
703 Support for full DMA access of devices with 32bit memory access only
704 on systems with more than 3GB. This is usually needed for USB,
705 sound, many IDE/SATA chipsets and some other devices.
706 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
707 based hardware IOMMU and a software bounce buffer based IOMMU used
708 on Intel systems and as fallback.
709 The code is only active when needed (enough memory and limited
710 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
711 too.
712
713config CALGARY_IOMMU
714 bool "IBM Calgary IOMMU support"
715 select SWIOTLB
716 depends on X86_64 && PCI && EXPERIMENTAL
717 ---help---
718 Support for hardware IOMMUs in IBM's xSeries x366 and x460
719 systems. Needed to run systems with more than 3GB of memory
720 properly with 32-bit PCI devices that do not support DAC
721 (Double Address Cycle). Calgary also supports bus level
722 isolation, where all DMAs pass through the IOMMU. This
723 prevents them from going anywhere except their intended
724 destination. This catches hard-to-find kernel bugs and
725 mis-behaving drivers and devices that do not use the DMA-API
726 properly to set up their DMA buffers. The IOMMU can be
727 turned off at boot time with the iommu=off parameter.
728 Normally the kernel will make the right choice by itself.
729 If unsure, say Y.
730
731config CALGARY_IOMMU_ENABLED_BY_DEFAULT
732 def_bool y
733 prompt "Should Calgary be enabled by default?"
734 depends on CALGARY_IOMMU
735 ---help---
736 Should Calgary be enabled by default? if you choose 'y', Calgary
737 will be used (if it exists). If you choose 'n', Calgary will not be
738 used even if it exists. If you choose 'n' and would like to use
739 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
740 If unsure, say Y.
741
742# need this always selected by IOMMU for the VIA workaround
743config SWIOTLB
744 def_bool y if X86_64
745 ---help---
746 Support for software bounce buffers used on x86-64 systems
747 which don't have a hardware IOMMU (e.g. the current generation
748 of Intel's x86-64 CPUs). Using this PCI devices which can only
749 access 32-bits of memory can be used on systems with more than
750 3 GB of memory. If unsure, say Y.
751
752config IOMMU_HELPER
753 def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU)
754
755config MAXSMP
756 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
757 depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
758 select CPUMASK_OFFSTACK
759 ---help---
760 Enable maximum number of CPUS and NUMA Nodes for this architecture.
761 If unsure, say N.
762
763config NR_CPUS
764 int "Maximum number of CPUs" if SMP && !MAXSMP
765 range 2 8 if SMP && X86_32 && !X86_BIGSMP
766 range 2 512 if SMP && !MAXSMP
767 default "1" if !SMP
768 default "4096" if MAXSMP
769 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
770 default "8" if SMP
771 ---help---
772 This allows you to specify the maximum number of CPUs which this
773 kernel will support. The maximum supported value is 512 and the
774 minimum value which makes sense is 2.
775
776 This is purely to save memory - each supported CPU adds
777 approximately eight kilobytes to the kernel image.
778
779config SCHED_SMT
780 bool "SMT (Hyperthreading) scheduler support"
781 depends on X86_HT
782 ---help---
783 SMT scheduler support improves the CPU scheduler's decision making
784 when dealing with Intel Pentium 4 chips with HyperThreading at a
785 cost of slightly increased overhead in some places. If unsure say
786 N here.
787
788config SCHED_MC
789 def_bool y
790 prompt "Multi-core scheduler support"
791 depends on X86_HT
792 ---help---
793 Multi-core scheduler support improves the CPU scheduler's decision
794 making when dealing with multi-core CPU chips at a cost of slightly
795 increased overhead in some places. If unsure say N here.
796
797config IRQ_TIME_ACCOUNTING
798 bool "Fine granularity task level IRQ time accounting"
799 default n
800 ---help---
801 Select this option to enable fine granularity task irq time
802 accounting. This is done by reading a timestamp on each
803 transitions between softirq and hardirq state, so there can be a
804 small performance impact.
805
806 If in doubt, say N here.
807
808source "kernel/Kconfig.preempt"
809
810config X86_UP_APIC
811 bool "Local APIC support on uniprocessors"
812 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
813 ---help---
814 A local APIC (Advanced Programmable Interrupt Controller) is an
815 integrated interrupt controller in the CPU. If you have a single-CPU
816 system which has a processor with a local APIC, you can say Y here to
817 enable and use it. If you say Y here even though your machine doesn't
818 have a local APIC, then the kernel will still run with no slowdown at
819 all. The local APIC supports CPU-generated self-interrupts (timer,
820 performance counters), and the NMI watchdog which detects hard
821 lockups.
822
823config X86_UP_IOAPIC
824 bool "IO-APIC support on uniprocessors"
825 depends on X86_UP_APIC
826 ---help---
827 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
828 SMP-capable replacement for PC-style interrupt controllers. Most
829 SMP systems and many recent uniprocessor systems have one.
830
831 If you have a single-CPU system with an IO-APIC, you can say Y here
832 to use it. If you say Y here even though your machine doesn't have
833 an IO-APIC, then the kernel will still run with no slowdown at all.
834
835config X86_LOCAL_APIC
836 def_bool y
837 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
838
839config X86_IO_APIC
840 def_bool y
841 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_IOAPIC
842
843config X86_VISWS_APIC
844 def_bool y
845 depends on X86_32 && X86_VISWS
846
847config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
848 bool "Reroute for broken boot IRQs"
849 depends on X86_IO_APIC
850 ---help---
851 This option enables a workaround that fixes a source of
852 spurious interrupts. This is recommended when threaded
853 interrupt handling is used on systems where the generation of
854 superfluous "boot interrupts" cannot be disabled.
855
856 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
857 entry in the chipset's IO-APIC is masked (as, e.g. the RT
858 kernel does during interrupt handling). On chipsets where this
859 boot IRQ generation cannot be disabled, this workaround keeps
860 the original IRQ line masked so that only the equivalent "boot
861 IRQ" is delivered to the CPUs. The workaround also tells the
862 kernel to set up the IRQ handler on the boot IRQ line. In this
863 way only one interrupt is delivered to the kernel. Otherwise
864 the spurious second interrupt may cause the kernel to bring
865 down (vital) interrupt lines.
866
867 Only affects "broken" chipsets. Interrupt sharing may be
868 increased on these systems.
869
870config X86_MCE
871 bool "Machine Check / overheating reporting"
872 ---help---
873 Machine Check support allows the processor to notify the
874 kernel if it detects a problem (e.g. overheating, data corruption).
875 The action the kernel takes depends on the severity of the problem,
876 ranging from warning messages to halting the machine.
877
878config X86_MCE_INTEL
879 def_bool y
880 prompt "Intel MCE features"
881 depends on X86_MCE && X86_LOCAL_APIC
882 ---help---
883 Additional support for intel specific MCE features such as
884 the thermal monitor.
885
886config X86_MCE_AMD
887 def_bool y
888 prompt "AMD MCE features"
889 depends on X86_MCE && X86_LOCAL_APIC
890 ---help---
891 Additional support for AMD specific MCE features such as
892 the DRAM Error Threshold.
893
894config X86_ANCIENT_MCE
895 bool "Support for old Pentium 5 / WinChip machine checks"
896 depends on X86_32 && X86_MCE
897 ---help---
898 Include support for machine check handling on old Pentium 5 or WinChip
899 systems. These typically need to be enabled explicitely on the command
900 line.
901
902config X86_MCE_THRESHOLD
903 depends on X86_MCE_AMD || X86_MCE_INTEL
904 def_bool y
905
906config X86_MCE_INJECT
907 depends on X86_MCE
908 tristate "Machine check injector support"
909 ---help---
910 Provide support for injecting machine checks for testing purposes.
911 If you don't know what a machine check is and you don't do kernel
912 QA it is safe to say n.
913
914config X86_THERMAL_VECTOR
915 def_bool y
916 depends on X86_MCE_INTEL
917
918config VM86
919 bool "Enable VM86 support" if EXPERT
920 default y
921 depends on X86_32
922 ---help---
923 This option is required by programs like DOSEMU to run 16-bit legacy
924 code on X86 processors. It also may be needed by software like
925 XFree86 to initialize some video cards via BIOS. Disabling this
926 option saves about 6k.
927
928config TOSHIBA
929 tristate "Toshiba Laptop support"
930 depends on X86_32
931 ---help---
932 This adds a driver to safely access the System Management Mode of
933 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
934 not work on models with a Phoenix BIOS. The System Management Mode
935 is used to set the BIOS and power saving options on Toshiba portables.
936
937 For information on utilities to make use of this driver see the
938 Toshiba Linux utilities web site at:
939 <http://www.buzzard.org.uk/toshiba/>.
940
941 Say Y if you intend to run this kernel on a Toshiba portable.
942 Say N otherwise.
943
944config I8K
945 tristate "Dell laptop support"
946 select HWMON
947 ---help---
948 This adds a driver to safely access the System Management Mode
949 of the CPU on the Dell Inspiron 8000. The System Management Mode
950 is used to read cpu temperature and cooling fan status and to
951 control the fans on the I8K portables.
952
953 This driver has been tested only on the Inspiron 8000 but it may
954 also work with other Dell laptops. You can force loading on other
955 models by passing the parameter `force=1' to the module. Use at
956 your own risk.
957
958 For information on utilities to make use of this driver see the
959 I8K Linux utilities web site at:
960 <http://people.debian.org/~dz/i8k/>
961
962 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
963 Say N otherwise.
964
965config X86_REBOOTFIXUPS
966 bool "Enable X86 board specific fixups for reboot"
967 depends on X86_32
968 ---help---
969 This enables chipset and/or board specific fixups to be done
970 in order to get reboot to work correctly. This is only needed on
971 some combinations of hardware and BIOS. The symptom, for which
972 this config is intended, is when reboot ends with a stalled/hung
973 system.
974
975 Currently, the only fixup is for the Geode machines using
976 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
977
978 Say Y if you want to enable the fixup. Currently, it's safe to
979 enable this option even if you don't need it.
980 Say N otherwise.
981
982config MICROCODE
983 tristate "/dev/cpu/microcode - microcode support"
984 select FW_LOADER
985 ---help---
986 If you say Y here, you will be able to update the microcode on
987 certain Intel and AMD processors. The Intel support is for the
988 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III,
989 Pentium 4, Xeon etc. The AMD support is for family 0x10 and
990 0x11 processors, e.g. Opteron, Phenom and Turion 64 Ultra.
991 You will obviously need the actual microcode binary data itself
992 which is not shipped with the Linux kernel.
993
994 This option selects the general module only, you need to select
995 at least one vendor specific module as well.
996
997 To compile this driver as a module, choose M here: the
998 module will be called microcode.
999
1000config MICROCODE_INTEL
1001 bool "Intel microcode patch loading support"
1002 depends on MICROCODE
1003 default MICROCODE
1004 select FW_LOADER
1005 ---help---
1006 This options enables microcode patch loading support for Intel
1007 processors.
1008
1009 For latest news and information on obtaining all the required
1010 Intel ingredients for this driver, check:
1011 <http://www.urbanmyth.org/microcode/>.
1012
1013config MICROCODE_AMD
1014 bool "AMD microcode patch loading support"
1015 depends on MICROCODE
1016 select FW_LOADER
1017 ---help---
1018 If you select this option, microcode patch loading support for AMD
1019 processors will be enabled.
1020
1021config MICROCODE_OLD_INTERFACE
1022 def_bool y
1023 depends on MICROCODE
1024
1025config X86_MSR
1026 tristate "/dev/cpu/*/msr - Model-specific register support"
1027 ---help---
1028 This device gives privileged processes access to the x86
1029 Model-Specific Registers (MSRs). It is a character device with
1030 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1031 MSR accesses are directed to a specific CPU on multi-processor
1032 systems.
1033
1034config X86_CPUID
1035 tristate "/dev/cpu/*/cpuid - CPU information support"
1036 ---help---
1037 This device gives processes access to the x86 CPUID instruction to
1038 be executed on a specific processor. It is a character device
1039 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1040 /dev/cpu/31/cpuid.
1041
1042choice
1043 prompt "High Memory Support"
1044 default HIGHMEM64G if X86_NUMAQ
1045 default HIGHMEM4G
1046 depends on X86_32
1047
1048config NOHIGHMEM
1049 bool "off"
1050 depends on !X86_NUMAQ
1051 ---help---
1052 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1053 However, the address space of 32-bit x86 processors is only 4
1054 Gigabytes large. That means that, if you have a large amount of
1055 physical memory, not all of it can be "permanently mapped" by the
1056 kernel. The physical memory that's not permanently mapped is called
1057 "high memory".
1058
1059 If you are compiling a kernel which will never run on a machine with
1060 more than 1 Gigabyte total physical RAM, answer "off" here (default
1061 choice and suitable for most users). This will result in a "3GB/1GB"
1062 split: 3GB are mapped so that each process sees a 3GB virtual memory
1063 space and the remaining part of the 4GB virtual memory space is used
1064 by the kernel to permanently map as much physical memory as
1065 possible.
1066
1067 If the machine has between 1 and 4 Gigabytes physical RAM, then
1068 answer "4GB" here.
1069
1070 If more than 4 Gigabytes is used then answer "64GB" here. This
1071 selection turns Intel PAE (Physical Address Extension) mode on.
1072 PAE implements 3-level paging on IA32 processors. PAE is fully
1073 supported by Linux, PAE mode is implemented on all recent Intel
1074 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1075 then the kernel will not boot on CPUs that don't support PAE!
1076
1077 The actual amount of total physical memory will either be
1078 auto detected or can be forced by using a kernel command line option
1079 such as "mem=256M". (Try "man bootparam" or see the documentation of
1080 your boot loader (lilo or loadlin) about how to pass options to the
1081 kernel at boot time.)
1082
1083 If unsure, say "off".
1084
1085config HIGHMEM4G
1086 bool "4GB"
1087 depends on !X86_NUMAQ
1088 ---help---
1089 Select this if you have a 32-bit processor and between 1 and 4
1090 gigabytes of physical RAM.
1091
1092config HIGHMEM64G
1093 bool "64GB"
1094 depends on !M386 && !M486
1095 select X86_PAE
1096 ---help---
1097 Select this if you have a 32-bit processor and more than 4
1098 gigabytes of physical RAM.
1099
1100endchoice
1101
1102choice
1103 depends on EXPERIMENTAL
1104 prompt "Memory split" if EXPERT
1105 default VMSPLIT_3G
1106 depends on X86_32
1107 ---help---
1108 Select the desired split between kernel and user memory.
1109
1110 If the address range available to the kernel is less than the
1111 physical memory installed, the remaining memory will be available
1112 as "high memory". Accessing high memory is a little more costly
1113 than low memory, as it needs to be mapped into the kernel first.
1114 Note that increasing the kernel address space limits the range
1115 available to user programs, making the address space there
1116 tighter. Selecting anything other than the default 3G/1G split
1117 will also likely make your kernel incompatible with binary-only
1118 kernel modules.
1119
1120 If you are not absolutely sure what you are doing, leave this
1121 option alone!
1122
1123 config VMSPLIT_3G
1124 bool "3G/1G user/kernel split"
1125 config VMSPLIT_3G_OPT
1126 depends on !X86_PAE
1127 bool "3G/1G user/kernel split (for full 1G low memory)"
1128 config VMSPLIT_2G
1129 bool "2G/2G user/kernel split"
1130 config VMSPLIT_2G_OPT
1131 depends on !X86_PAE
1132 bool "2G/2G user/kernel split (for full 2G low memory)"
1133 config VMSPLIT_1G
1134 bool "1G/3G user/kernel split"
1135endchoice
1136
1137config PAGE_OFFSET
1138 hex
1139 default 0xB0000000 if VMSPLIT_3G_OPT
1140 default 0x80000000 if VMSPLIT_2G
1141 default 0x78000000 if VMSPLIT_2G_OPT
1142 default 0x40000000 if VMSPLIT_1G
1143 default 0xC0000000
1144 depends on X86_32
1145
1146config HIGHMEM
1147 def_bool y
1148 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1149
1150config X86_PAE
1151 bool "PAE (Physical Address Extension) Support"
1152 depends on X86_32 && !HIGHMEM4G
1153 ---help---
1154 PAE is required for NX support, and furthermore enables
1155 larger swapspace support for non-overcommit purposes. It
1156 has the cost of more pagetable lookup overhead, and also
1157 consumes more pagetable space per process.
1158
1159config ARCH_PHYS_ADDR_T_64BIT
1160 def_bool X86_64 || X86_PAE
1161
1162config ARCH_DMA_ADDR_T_64BIT
1163 def_bool X86_64 || HIGHMEM64G
1164
1165config DIRECT_GBPAGES
1166 bool "Enable 1GB pages for kernel pagetables" if EXPERT
1167 default y
1168 depends on X86_64
1169 ---help---
1170 Allow the kernel linear mapping to use 1GB pages on CPUs that
1171 support it. This can improve the kernel's performance a tiny bit by
1172 reducing TLB pressure. If in doubt, say "Y".
1173
1174# Common NUMA Features
1175config NUMA
1176 bool "Numa Memory Allocation and Scheduler Support"
1177 depends on SMP
1178 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1179 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1180 ---help---
1181 Enable NUMA (Non Uniform Memory Access) support.
1182
1183 The kernel will try to allocate memory used by a CPU on the
1184 local memory controller of the CPU and add some more
1185 NUMA awareness to the kernel.
1186
1187 For 64-bit this is recommended if the system is Intel Core i7
1188 (or later), AMD Opteron, or EM64T NUMA.
1189
1190 For 32-bit this is only needed on (rare) 32-bit-only platforms
1191 that support NUMA topologies, such as NUMAQ / Summit, or if you
1192 boot a 32-bit kernel on a 64-bit NUMA platform.
1193
1194 Otherwise, you should say N.
1195
1196comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1197 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1198
1199config AMD_NUMA
1200 def_bool y
1201 prompt "Old style AMD Opteron NUMA detection"
1202 depends on X86_64 && NUMA && PCI
1203 ---help---
1204 Enable AMD NUMA node topology detection. You should say Y here if
1205 you have a multi processor AMD system. This uses an old method to
1206 read the NUMA configuration directly from the builtin Northbridge
1207 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1208 which also takes priority if both are compiled in.
1209
1210config X86_64_ACPI_NUMA
1211 def_bool y
1212 prompt "ACPI NUMA detection"
1213 depends on X86_64 && NUMA && ACPI && PCI
1214 select ACPI_NUMA
1215 ---help---
1216 Enable ACPI SRAT based node topology detection.
1217
1218# Some NUMA nodes have memory ranges that span
1219# other nodes. Even though a pfn is valid and
1220# between a node's start and end pfns, it may not
1221# reside on that node. See memmap_init_zone()
1222# for details.
1223config NODES_SPAN_OTHER_NODES
1224 def_bool y
1225 depends on X86_64_ACPI_NUMA
1226
1227config NUMA_EMU
1228 bool "NUMA emulation"
1229 depends on NUMA
1230 ---help---
1231 Enable NUMA emulation. A flat machine will be split
1232 into virtual nodes when booted with "numa=fake=N", where N is the
1233 number of nodes. This is only useful for debugging.
1234
1235config NODES_SHIFT
1236 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1237 range 1 10
1238 default "10" if MAXSMP
1239 default "6" if X86_64
1240 default "4" if X86_NUMAQ
1241 default "3"
1242 depends on NEED_MULTIPLE_NODES
1243 ---help---
1244 Specify the maximum number of NUMA Nodes available on the target
1245 system. Increases memory reserved to accommodate various tables.
1246
1247config HAVE_ARCH_ALLOC_REMAP
1248 def_bool y
1249 depends on X86_32 && NUMA
1250
1251config ARCH_HAVE_MEMORY_PRESENT
1252 def_bool y
1253 depends on X86_32 && DISCONTIGMEM
1254
1255config NEED_NODE_MEMMAP_SIZE
1256 def_bool y
1257 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1258
1259config ARCH_FLATMEM_ENABLE
1260 def_bool y
1261 depends on X86_32 && !NUMA
1262
1263config ARCH_DISCONTIGMEM_ENABLE
1264 def_bool y
1265 depends on NUMA && X86_32
1266
1267config ARCH_DISCONTIGMEM_DEFAULT
1268 def_bool y
1269 depends on NUMA && X86_32
1270
1271config ARCH_SPARSEMEM_ENABLE
1272 def_bool y
1273 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_32) || X86_32_NON_STANDARD
1274 select SPARSEMEM_STATIC if X86_32
1275 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1276
1277config ARCH_SPARSEMEM_DEFAULT
1278 def_bool y
1279 depends on X86_64
1280
1281config ARCH_SELECT_MEMORY_MODEL
1282 def_bool y
1283 depends on ARCH_SPARSEMEM_ENABLE
1284
1285config ARCH_MEMORY_PROBE
1286 def_bool X86_64
1287 depends on MEMORY_HOTPLUG
1288
1289config ARCH_PROC_KCORE_TEXT
1290 def_bool y
1291 depends on X86_64 && PROC_KCORE
1292
1293config ILLEGAL_POINTER_VALUE
1294 hex
1295 default 0 if X86_32
1296 default 0xdead000000000000 if X86_64
1297
1298source "mm/Kconfig"
1299
1300config HIGHPTE
1301 bool "Allocate 3rd-level pagetables from highmem"
1302 depends on HIGHMEM
1303 ---help---
1304 The VM uses one page table entry for each page of physical memory.
1305 For systems with a lot of RAM, this can be wasteful of precious
1306 low memory. Setting this option will put user-space page table
1307 entries in high memory.
1308
1309config X86_CHECK_BIOS_CORRUPTION
1310 bool "Check for low memory corruption"
1311 ---help---
1312 Periodically check for memory corruption in low memory, which
1313 is suspected to be caused by BIOS. Even when enabled in the
1314 configuration, it is disabled at runtime. Enable it by
1315 setting "memory_corruption_check=1" on the kernel command
1316 line. By default it scans the low 64k of memory every 60
1317 seconds; see the memory_corruption_check_size and
1318 memory_corruption_check_period parameters in
1319 Documentation/kernel-parameters.txt to adjust this.
1320
1321 When enabled with the default parameters, this option has
1322 almost no overhead, as it reserves a relatively small amount
1323 of memory and scans it infrequently. It both detects corruption
1324 and prevents it from affecting the running system.
1325
1326 It is, however, intended as a diagnostic tool; if repeatable
1327 BIOS-originated corruption always affects the same memory,
1328 you can use memmap= to prevent the kernel from using that
1329 memory.
1330
1331config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1332 bool "Set the default setting of memory_corruption_check"
1333 depends on X86_CHECK_BIOS_CORRUPTION
1334 default y
1335 ---help---
1336 Set whether the default state of memory_corruption_check is
1337 on or off.
1338
1339config X86_RESERVE_LOW
1340 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1341 default 64
1342 range 4 640
1343 ---help---
1344 Specify the amount of low memory to reserve for the BIOS.
1345
1346 The first page contains BIOS data structures that the kernel
1347 must not use, so that page must always be reserved.
1348
1349 By default we reserve the first 64K of physical RAM, as a
1350 number of BIOSes are known to corrupt that memory range
1351 during events such as suspend/resume or monitor cable
1352 insertion, so it must not be used by the kernel.
1353
1354 You can set this to 4 if you are absolutely sure that you
1355 trust the BIOS to get all its memory reservations and usages
1356 right. If you know your BIOS have problems beyond the
1357 default 64K area, you can set this to 640 to avoid using the
1358 entire low memory range.
1359
1360 If you have doubts about the BIOS (e.g. suspend/resume does
1361 not work or there's kernel crashes after certain hardware
1362 hotplug events) then you might want to enable
1363 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1364 typical corruption patterns.
1365
1366 Leave this to the default value of 64 if you are unsure.
1367
1368config MATH_EMULATION
1369 bool
1370 prompt "Math emulation" if X86_32
1371 ---help---
1372 Linux can emulate a math coprocessor (used for floating point
1373 operations) if you don't have one. 486DX and Pentium processors have
1374 a math coprocessor built in, 486SX and 386 do not, unless you added
1375 a 487DX or 387, respectively. (The messages during boot time can
1376 give you some hints here ["man dmesg"].) Everyone needs either a
1377 coprocessor or this emulation.
1378
1379 If you don't have a math coprocessor, you need to say Y here; if you
1380 say Y here even though you have a coprocessor, the coprocessor will
1381 be used nevertheless. (This behavior can be changed with the kernel
1382 command line option "no387", which comes handy if your coprocessor
1383 is broken. Try "man bootparam" or see the documentation of your boot
1384 loader (lilo or loadlin) about how to pass options to the kernel at
1385 boot time.) This means that it is a good idea to say Y here if you
1386 intend to use this kernel on different machines.
1387
1388 More information about the internals of the Linux math coprocessor
1389 emulation can be found in <file:arch/x86/math-emu/README>.
1390
1391 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1392 kernel, it won't hurt.
1393
1394config MTRR
1395 def_bool y
1396 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1397 ---help---
1398 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1399 the Memory Type Range Registers (MTRRs) may be used to control
1400 processor access to memory ranges. This is most useful if you have
1401 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1402 allows bus write transfers to be combined into a larger transfer
1403 before bursting over the PCI/AGP bus. This can increase performance
1404 of image write operations 2.5 times or more. Saying Y here creates a
1405 /proc/mtrr file which may be used to manipulate your processor's
1406 MTRRs. Typically the X server should use this.
1407
1408 This code has a reasonably generic interface so that similar
1409 control registers on other processors can be easily supported
1410 as well:
1411
1412 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1413 Registers (ARRs) which provide a similar functionality to MTRRs. For
1414 these, the ARRs are used to emulate the MTRRs.
1415 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1416 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1417 write-combining. All of these processors are supported by this code
1418 and it makes sense to say Y here if you have one of them.
1419
1420 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1421 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1422 can lead to all sorts of problems, so it's good to say Y here.
1423
1424 You can safely say Y even if your machine doesn't have MTRRs, you'll
1425 just add about 9 KB to your kernel.
1426
1427 See <file:Documentation/x86/mtrr.txt> for more information.
1428
1429config MTRR_SANITIZER
1430 def_bool y
1431 prompt "MTRR cleanup support"
1432 depends on MTRR
1433 ---help---
1434 Convert MTRR layout from continuous to discrete, so X drivers can
1435 add writeback entries.
1436
1437 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1438 The largest mtrr entry size for a continuous block can be set with
1439 mtrr_chunk_size.
1440
1441 If unsure, say Y.
1442
1443config MTRR_SANITIZER_ENABLE_DEFAULT
1444 int "MTRR cleanup enable value (0-1)"
1445 range 0 1
1446 default "0"
1447 depends on MTRR_SANITIZER
1448 ---help---
1449 Enable mtrr cleanup default value
1450
1451config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1452 int "MTRR cleanup spare reg num (0-7)"
1453 range 0 7
1454 default "1"
1455 depends on MTRR_SANITIZER
1456 ---help---
1457 mtrr cleanup spare entries default, it can be changed via
1458 mtrr_spare_reg_nr=N on the kernel command line.
1459
1460config X86_PAT
1461 def_bool y
1462 prompt "x86 PAT support" if EXPERT
1463 depends on MTRR
1464 ---help---
1465 Use PAT attributes to setup page level cache control.
1466
1467 PATs are the modern equivalents of MTRRs and are much more
1468 flexible than MTRRs.
1469
1470 Say N here if you see bootup problems (boot crash, boot hang,
1471 spontaneous reboots) or a non-working video driver.
1472
1473 If unsure, say Y.
1474
1475config ARCH_USES_PG_UNCACHED
1476 def_bool y
1477 depends on X86_PAT
1478
1479config ARCH_RANDOM
1480 def_bool y
1481 prompt "x86 architectural random number generator" if EXPERT
1482 ---help---
1483 Enable the x86 architectural RDRAND instruction
1484 (Intel Bull Mountain technology) to generate random numbers.
1485 If supported, this is a high bandwidth, cryptographically
1486 secure hardware random number generator.
1487
1488config EFI
1489 bool "EFI runtime service support"
1490 depends on ACPI
1491 ---help---
1492 This enables the kernel to use EFI runtime services that are
1493 available (such as the EFI variable services).
1494
1495 This option is only useful on systems that have EFI firmware.
1496 In addition, you should use the latest ELILO loader available
1497 at <http://elilo.sourceforge.net> in order to take advantage
1498 of EFI runtime services. However, even with this option, the
1499 resultant kernel should continue to boot on existing non-EFI
1500 platforms.
1501
1502config EFI_STUB
1503 bool "EFI stub support"
1504 depends on EFI
1505 ---help---
1506 This kernel feature allows a bzImage to be loaded directly
1507 by EFI firmware without the use of a bootloader.
1508
1509 See Documentation/x86/efi-stub.txt for more information.
1510
1511config SECCOMP
1512 def_bool y
1513 prompt "Enable seccomp to safely compute untrusted bytecode"
1514 ---help---
1515 This kernel feature is useful for number crunching applications
1516 that may need to compute untrusted bytecode during their
1517 execution. By using pipes or other transports made available to
1518 the process as file descriptors supporting the read/write
1519 syscalls, it's possible to isolate those applications in
1520 their own address space using seccomp. Once seccomp is
1521 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1522 and the task is only allowed to execute a few safe syscalls
1523 defined by each seccomp mode.
1524
1525 If unsure, say Y. Only embedded should say N here.
1526
1527config CC_STACKPROTECTOR
1528 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1529 ---help---
1530 This option turns on the -fstack-protector GCC feature. This
1531 feature puts, at the beginning of functions, a canary value on
1532 the stack just before the return address, and validates
1533 the value just before actually returning. Stack based buffer
1534 overflows (that need to overwrite this return address) now also
1535 overwrite the canary, which gets detected and the attack is then
1536 neutralized via a kernel panic.
1537
1538 This feature requires gcc version 4.2 or above, or a distribution
1539 gcc with the feature backported. Older versions are automatically
1540 detected and for those versions, this configuration option is
1541 ignored. (and a warning is printed during bootup)
1542
1543source kernel/Kconfig.hz
1544
1545config KEXEC
1546 bool "kexec system call"
1547 ---help---
1548 kexec is a system call that implements the ability to shutdown your
1549 current kernel, and to start another kernel. It is like a reboot
1550 but it is independent of the system firmware. And like a reboot
1551 you can start any kernel with it, not just Linux.
1552
1553 The name comes from the similarity to the exec system call.
1554
1555 It is an ongoing process to be certain the hardware in a machine
1556 is properly shutdown, so do not be surprised if this code does not
1557 initially work for you. It may help to enable device hotplugging
1558 support. As of this writing the exact hardware interface is
1559 strongly in flux, so no good recommendation can be made.
1560
1561config CRASH_DUMP
1562 bool "kernel crash dumps"
1563 depends on X86_64 || (X86_32 && HIGHMEM)
1564 ---help---
1565 Generate crash dump after being started by kexec.
1566 This should be normally only set in special crash dump kernels
1567 which are loaded in the main kernel with kexec-tools into
1568 a specially reserved region and then later executed after
1569 a crash by kdump/kexec. The crash dump kernel must be compiled
1570 to a memory address not used by the main kernel or BIOS using
1571 PHYSICAL_START, or it must be built as a relocatable image
1572 (CONFIG_RELOCATABLE=y).
1573 For more details see Documentation/kdump/kdump.txt
1574
1575config KEXEC_JUMP
1576 bool "kexec jump (EXPERIMENTAL)"
1577 depends on EXPERIMENTAL
1578 depends on KEXEC && HIBERNATION
1579 ---help---
1580 Jump between original kernel and kexeced kernel and invoke
1581 code in physical address mode via KEXEC
1582
1583config PHYSICAL_START
1584 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1585 default "0x1000000"
1586 ---help---
1587 This gives the physical address where the kernel is loaded.
1588
1589 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1590 bzImage will decompress itself to above physical address and
1591 run from there. Otherwise, bzImage will run from the address where
1592 it has been loaded by the boot loader and will ignore above physical
1593 address.
1594
1595 In normal kdump cases one does not have to set/change this option
1596 as now bzImage can be compiled as a completely relocatable image
1597 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1598 address. This option is mainly useful for the folks who don't want
1599 to use a bzImage for capturing the crash dump and want to use a
1600 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1601 to be specifically compiled to run from a specific memory area
1602 (normally a reserved region) and this option comes handy.
1603
1604 So if you are using bzImage for capturing the crash dump,
1605 leave the value here unchanged to 0x1000000 and set
1606 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1607 for capturing the crash dump change this value to start of
1608 the reserved region. In other words, it can be set based on
1609 the "X" value as specified in the "crashkernel=YM@XM"
1610 command line boot parameter passed to the panic-ed
1611 kernel. Please take a look at Documentation/kdump/kdump.txt
1612 for more details about crash dumps.
1613
1614 Usage of bzImage for capturing the crash dump is recommended as
1615 one does not have to build two kernels. Same kernel can be used
1616 as production kernel and capture kernel. Above option should have
1617 gone away after relocatable bzImage support is introduced. But it
1618 is present because there are users out there who continue to use
1619 vmlinux for dump capture. This option should go away down the
1620 line.
1621
1622 Don't change this unless you know what you are doing.
1623
1624config RELOCATABLE
1625 bool "Build a relocatable kernel"
1626 default y
1627 ---help---
1628 This builds a kernel image that retains relocation information
1629 so it can be loaded someplace besides the default 1MB.
1630 The relocations tend to make the kernel binary about 10% larger,
1631 but are discarded at runtime.
1632
1633 One use is for the kexec on panic case where the recovery kernel
1634 must live at a different physical address than the primary
1635 kernel.
1636
1637 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1638 it has been loaded at and the compile time physical address
1639 (CONFIG_PHYSICAL_START) is ignored.
1640
1641# Relocation on x86-32 needs some additional build support
1642config X86_NEED_RELOCS
1643 def_bool y
1644 depends on X86_32 && RELOCATABLE
1645
1646config PHYSICAL_ALIGN
1647 hex "Alignment value to which kernel should be aligned" if X86_32
1648 default "0x1000000"
1649 range 0x2000 0x1000000
1650 ---help---
1651 This value puts the alignment restrictions on physical address
1652 where kernel is loaded and run from. Kernel is compiled for an
1653 address which meets above alignment restriction.
1654
1655 If bootloader loads the kernel at a non-aligned address and
1656 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1657 address aligned to above value and run from there.
1658
1659 If bootloader loads the kernel at a non-aligned address and
1660 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1661 load address and decompress itself to the address it has been
1662 compiled for and run from there. The address for which kernel is
1663 compiled already meets above alignment restrictions. Hence the
1664 end result is that kernel runs from a physical address meeting
1665 above alignment restrictions.
1666
1667 Don't change this unless you know what you are doing.
1668
1669config HOTPLUG_CPU
1670 bool "Support for hot-pluggable CPUs"
1671 depends on SMP && HOTPLUG
1672 ---help---
1673 Say Y here to allow turning CPUs off and on. CPUs can be
1674 controlled through /sys/devices/system/cpu.
1675 ( Note: power management support will enable this option
1676 automatically on SMP systems. )
1677 Say N if you want to disable CPU hotplug.
1678
1679config COMPAT_VDSO
1680 def_bool y
1681 prompt "Compat VDSO support"
1682 depends on X86_32 || IA32_EMULATION
1683 ---help---
1684 Map the 32-bit VDSO to the predictable old-style address too.
1685
1686 Say N here if you are running a sufficiently recent glibc
1687 version (2.3.3 or later), to remove the high-mapped
1688 VDSO mapping and to exclusively use the randomized VDSO.
1689
1690 If unsure, say Y.
1691
1692config CMDLINE_BOOL
1693 bool "Built-in kernel command line"
1694 ---help---
1695 Allow for specifying boot arguments to the kernel at
1696 build time. On some systems (e.g. embedded ones), it is
1697 necessary or convenient to provide some or all of the
1698 kernel boot arguments with the kernel itself (that is,
1699 to not rely on the boot loader to provide them.)
1700
1701 To compile command line arguments into the kernel,
1702 set this option to 'Y', then fill in the
1703 the boot arguments in CONFIG_CMDLINE.
1704
1705 Systems with fully functional boot loaders (i.e. non-embedded)
1706 should leave this option set to 'N'.
1707
1708config CMDLINE
1709 string "Built-in kernel command string"
1710 depends on CMDLINE_BOOL
1711 default ""
1712 ---help---
1713 Enter arguments here that should be compiled into the kernel
1714 image and used at boot time. If the boot loader provides a
1715 command line at boot time, it is appended to this string to
1716 form the full kernel command line, when the system boots.
1717
1718 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1719 change this behavior.
1720
1721 In most cases, the command line (whether built-in or provided
1722 by the boot loader) should specify the device for the root
1723 file system.
1724
1725config CMDLINE_OVERRIDE
1726 bool "Built-in command line overrides boot loader arguments"
1727 depends on CMDLINE_BOOL
1728 ---help---
1729 Set this option to 'Y' to have the kernel ignore the boot loader
1730 command line, and use ONLY the built-in command line.
1731
1732 This is used to work around broken boot loaders. This should
1733 be set to 'N' under normal conditions.
1734
1735endmenu
1736
1737config ARCH_ENABLE_MEMORY_HOTPLUG
1738 def_bool y
1739 depends on X86_64 || (X86_32 && HIGHMEM)
1740
1741config ARCH_ENABLE_MEMORY_HOTREMOVE
1742 def_bool y
1743 depends on MEMORY_HOTPLUG
1744
1745config USE_PERCPU_NUMA_NODE_ID
1746 def_bool y
1747 depends on NUMA
1748
1749menu "Power management and ACPI options"
1750
1751config ARCH_HIBERNATION_HEADER
1752 def_bool y
1753 depends on X86_64 && HIBERNATION
1754
1755source "kernel/power/Kconfig"
1756
1757source "drivers/acpi/Kconfig"
1758
1759source "drivers/sfi/Kconfig"
1760
1761config X86_APM_BOOT
1762 def_bool y
1763 depends on APM
1764
1765menuconfig APM
1766 tristate "APM (Advanced Power Management) BIOS support"
1767 depends on X86_32 && PM_SLEEP
1768 ---help---
1769 APM is a BIOS specification for saving power using several different
1770 techniques. This is mostly useful for battery powered laptops with
1771 APM compliant BIOSes. If you say Y here, the system time will be
1772 reset after a RESUME operation, the /proc/apm device will provide
1773 battery status information, and user-space programs will receive
1774 notification of APM "events" (e.g. battery status change).
1775
1776 If you select "Y" here, you can disable actual use of the APM
1777 BIOS by passing the "apm=off" option to the kernel at boot time.
1778
1779 Note that the APM support is almost completely disabled for
1780 machines with more than one CPU.
1781
1782 In order to use APM, you will need supporting software. For location
1783 and more information, read <file:Documentation/power/apm-acpi.txt>
1784 and the Battery Powered Linux mini-HOWTO, available from
1785 <http://www.tldp.org/docs.html#howto>.
1786
1787 This driver does not spin down disk drives (see the hdparm(8)
1788 manpage ("man 8 hdparm") for that), and it doesn't turn off
1789 VESA-compliant "green" monitors.
1790
1791 This driver does not support the TI 4000M TravelMate and the ACER
1792 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1793 desktop machines also don't have compliant BIOSes, and this driver
1794 may cause those machines to panic during the boot phase.
1795
1796 Generally, if you don't have a battery in your machine, there isn't
1797 much point in using this driver and you should say N. If you get
1798 random kernel OOPSes or reboots that don't seem to be related to
1799 anything, try disabling/enabling this option (or disabling/enabling
1800 APM in your BIOS).
1801
1802 Some other things you should try when experiencing seemingly random,
1803 "weird" problems:
1804
1805 1) make sure that you have enough swap space and that it is
1806 enabled.
1807 2) pass the "no-hlt" option to the kernel
1808 3) switch on floating point emulation in the kernel and pass
1809 the "no387" option to the kernel
1810 4) pass the "floppy=nodma" option to the kernel
1811 5) pass the "mem=4M" option to the kernel (thereby disabling
1812 all but the first 4 MB of RAM)
1813 6) make sure that the CPU is not over clocked.
1814 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1815 8) disable the cache from your BIOS settings
1816 9) install a fan for the video card or exchange video RAM
1817 10) install a better fan for the CPU
1818 11) exchange RAM chips
1819 12) exchange the motherboard.
1820
1821 To compile this driver as a module, choose M here: the
1822 module will be called apm.
1823
1824if APM
1825
1826config APM_IGNORE_USER_SUSPEND
1827 bool "Ignore USER SUSPEND"
1828 ---help---
1829 This option will ignore USER SUSPEND requests. On machines with a
1830 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1831 series notebooks, it is necessary to say Y because of a BIOS bug.
1832
1833config APM_DO_ENABLE
1834 bool "Enable PM at boot time"
1835 ---help---
1836 Enable APM features at boot time. From page 36 of the APM BIOS
1837 specification: "When disabled, the APM BIOS does not automatically
1838 power manage devices, enter the Standby State, enter the Suspend
1839 State, or take power saving steps in response to CPU Idle calls."
1840 This driver will make CPU Idle calls when Linux is idle (unless this
1841 feature is turned off -- see "Do CPU IDLE calls", below). This
1842 should always save battery power, but more complicated APM features
1843 will be dependent on your BIOS implementation. You may need to turn
1844 this option off if your computer hangs at boot time when using APM
1845 support, or if it beeps continuously instead of suspending. Turn
1846 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1847 T400CDT. This is off by default since most machines do fine without
1848 this feature.
1849
1850config APM_CPU_IDLE
1851 bool "Make CPU Idle calls when idle"
1852 ---help---
1853 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1854 On some machines, this can activate improved power savings, such as
1855 a slowed CPU clock rate, when the machine is idle. These idle calls
1856 are made after the idle loop has run for some length of time (e.g.,
1857 333 mS). On some machines, this will cause a hang at boot time or
1858 whenever the CPU becomes idle. (On machines with more than one CPU,
1859 this option does nothing.)
1860
1861config APM_DISPLAY_BLANK
1862 bool "Enable console blanking using APM"
1863 ---help---
1864 Enable console blanking using the APM. Some laptops can use this to
1865 turn off the LCD backlight when the screen blanker of the Linux
1866 virtual console blanks the screen. Note that this is only used by
1867 the virtual console screen blanker, and won't turn off the backlight
1868 when using the X Window system. This also doesn't have anything to
1869 do with your VESA-compliant power-saving monitor. Further, this
1870 option doesn't work for all laptops -- it might not turn off your
1871 backlight at all, or it might print a lot of errors to the console,
1872 especially if you are using gpm.
1873
1874config APM_ALLOW_INTS
1875 bool "Allow interrupts during APM BIOS calls"
1876 ---help---
1877 Normally we disable external interrupts while we are making calls to
1878 the APM BIOS as a measure to lessen the effects of a badly behaving
1879 BIOS implementation. The BIOS should reenable interrupts if it
1880 needs to. Unfortunately, some BIOSes do not -- especially those in
1881 many of the newer IBM Thinkpads. If you experience hangs when you
1882 suspend, try setting this to Y. Otherwise, say N.
1883
1884endif # APM
1885
1886source "drivers/cpufreq/Kconfig"
1887
1888source "drivers/cpuidle/Kconfig"
1889
1890source "drivers/idle/Kconfig"
1891
1892endmenu
1893
1894
1895menu "Bus options (PCI etc.)"
1896
1897config PCI
1898 bool "PCI support"
1899 default y
1900 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1901 ---help---
1902 Find out whether you have a PCI motherboard. PCI is the name of a
1903 bus system, i.e. the way the CPU talks to the other stuff inside
1904 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1905 VESA. If you have PCI, say Y, otherwise N.
1906
1907choice
1908 prompt "PCI access mode"
1909 depends on X86_32 && PCI
1910 default PCI_GOANY
1911 ---help---
1912 On PCI systems, the BIOS can be used to detect the PCI devices and
1913 determine their configuration. However, some old PCI motherboards
1914 have BIOS bugs and may crash if this is done. Also, some embedded
1915 PCI-based systems don't have any BIOS at all. Linux can also try to
1916 detect the PCI hardware directly without using the BIOS.
1917
1918 With this option, you can specify how Linux should detect the
1919 PCI devices. If you choose "BIOS", the BIOS will be used,
1920 if you choose "Direct", the BIOS won't be used, and if you
1921 choose "MMConfig", then PCI Express MMCONFIG will be used.
1922 If you choose "Any", the kernel will try MMCONFIG, then the
1923 direct access method and falls back to the BIOS if that doesn't
1924 work. If unsure, go with the default, which is "Any".
1925
1926config PCI_GOBIOS
1927 bool "BIOS"
1928
1929config PCI_GOMMCONFIG
1930 bool "MMConfig"
1931
1932config PCI_GODIRECT
1933 bool "Direct"
1934
1935config PCI_GOOLPC
1936 bool "OLPC XO-1"
1937 depends on OLPC
1938
1939config PCI_GOANY
1940 bool "Any"
1941
1942endchoice
1943
1944config PCI_BIOS
1945 def_bool y
1946 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
1947
1948# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1949config PCI_DIRECT
1950 def_bool y
1951 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
1952
1953config PCI_MMCONFIG
1954 def_bool y
1955 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
1956
1957config PCI_OLPC
1958 def_bool y
1959 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
1960
1961config PCI_XEN
1962 def_bool y
1963 depends on PCI && XEN
1964 select SWIOTLB_XEN
1965
1966config PCI_DOMAINS
1967 def_bool y
1968 depends on PCI
1969
1970config PCI_MMCONFIG
1971 bool "Support mmconfig PCI config space access"
1972 depends on X86_64 && PCI && ACPI
1973
1974config PCI_CNB20LE_QUIRK
1975 bool "Read CNB20LE Host Bridge Windows" if EXPERT
1976 default n
1977 depends on PCI && EXPERIMENTAL
1978 help
1979 Read the PCI windows out of the CNB20LE host bridge. This allows
1980 PCI hotplug to work on systems with the CNB20LE chipset which do
1981 not have ACPI.
1982
1983 There's no public spec for this chipset, and this functionality
1984 is known to be incomplete.
1985
1986 You should say N unless you know you need this.
1987
1988source "drivers/pci/pcie/Kconfig"
1989
1990source "drivers/pci/Kconfig"
1991
1992# x86_64 have no ISA slots, but can have ISA-style DMA.
1993config ISA_DMA_API
1994 bool "ISA-style DMA support" if (X86_64 && EXPERT)
1995 default y
1996 help
1997 Enables ISA-style DMA support for devices requiring such controllers.
1998 If unsure, say Y.
1999
2000if X86_32
2001
2002config ISA
2003 bool "ISA support"
2004 ---help---
2005 Find out whether you have ISA slots on your motherboard. ISA is the
2006 name of a bus system, i.e. the way the CPU talks to the other stuff
2007 inside your box. Other bus systems are PCI, EISA, MicroChannel
2008 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2009 newer boards don't support it. If you have ISA, say Y, otherwise N.
2010
2011config EISA
2012 bool "EISA support"
2013 depends on ISA
2014 ---help---
2015 The Extended Industry Standard Architecture (EISA) bus was
2016 developed as an open alternative to the IBM MicroChannel bus.
2017
2018 The EISA bus provided some of the features of the IBM MicroChannel
2019 bus while maintaining backward compatibility with cards made for
2020 the older ISA bus. The EISA bus saw limited use between 1988 and
2021 1995 when it was made obsolete by the PCI bus.
2022
2023 Say Y here if you are building a kernel for an EISA-based machine.
2024
2025 Otherwise, say N.
2026
2027source "drivers/eisa/Kconfig"
2028
2029config SCx200
2030 tristate "NatSemi SCx200 support"
2031 ---help---
2032 This provides basic support for National Semiconductor's
2033 (now AMD's) Geode processors. The driver probes for the
2034 PCI-IDs of several on-chip devices, so its a good dependency
2035 for other scx200_* drivers.
2036
2037 If compiled as a module, the driver is named scx200.
2038
2039config SCx200HR_TIMER
2040 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2041 depends on SCx200
2042 default y
2043 ---help---
2044 This driver provides a clocksource built upon the on-chip
2045 27MHz high-resolution timer. Its also a workaround for
2046 NSC Geode SC-1100's buggy TSC, which loses time when the
2047 processor goes idle (as is done by the scheduler). The
2048 other workaround is idle=poll boot option.
2049
2050config OLPC
2051 bool "One Laptop Per Child support"
2052 depends on !X86_PAE
2053 select GPIOLIB
2054 select OF
2055 select OF_PROMTREE
2056 select IRQ_DOMAIN
2057 ---help---
2058 Add support for detecting the unique features of the OLPC
2059 XO hardware.
2060
2061config OLPC_XO1_PM
2062 bool "OLPC XO-1 Power Management"
2063 depends on OLPC && MFD_CS5535 && PM_SLEEP
2064 select MFD_CORE
2065 ---help---
2066 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2067
2068config OLPC_XO1_RTC
2069 bool "OLPC XO-1 Real Time Clock"
2070 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2071 ---help---
2072 Add support for the XO-1 real time clock, which can be used as a
2073 programmable wakeup source.
2074
2075config OLPC_XO1_SCI
2076 bool "OLPC XO-1 SCI extras"
2077 depends on OLPC && OLPC_XO1_PM
2078 select POWER_SUPPLY
2079 select GPIO_CS5535
2080 select MFD_CORE
2081 ---help---
2082 Add support for SCI-based features of the OLPC XO-1 laptop:
2083 - EC-driven system wakeups
2084 - Power button
2085 - Ebook switch
2086 - Lid switch
2087 - AC adapter status updates
2088 - Battery status updates
2089
2090config OLPC_XO15_SCI
2091 bool "OLPC XO-1.5 SCI extras"
2092 depends on OLPC && ACPI
2093 select POWER_SUPPLY
2094 ---help---
2095 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2096 - EC-driven system wakeups
2097 - AC adapter status updates
2098 - Battery status updates
2099
2100config ALIX
2101 bool "PCEngines ALIX System Support (LED setup)"
2102 select GPIOLIB
2103 ---help---
2104 This option enables system support for the PCEngines ALIX.
2105 At present this just sets up LEDs for GPIO control on
2106 ALIX2/3/6 boards. However, other system specific setup should
2107 get added here.
2108
2109 Note: You must still enable the drivers for GPIO and LED support
2110 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2111
2112 Note: You have to set alix.force=1 for boards with Award BIOS.
2113
2114config NET5501
2115 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2116 select GPIOLIB
2117 ---help---
2118 This option enables system support for the Soekris Engineering net5501.
2119
2120config GEOS
2121 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2122 select GPIOLIB
2123 depends on DMI
2124 ---help---
2125 This option enables system support for the Traverse Technologies GEOS.
2126
2127endif # X86_32
2128
2129config AMD_NB
2130 def_bool y
2131 depends on CPU_SUP_AMD && PCI
2132
2133source "drivers/pcmcia/Kconfig"
2134
2135source "drivers/pci/hotplug/Kconfig"
2136
2137config RAPIDIO
2138 bool "RapidIO support"
2139 depends on PCI
2140 default n
2141 help
2142 If you say Y here, the kernel will include drivers and
2143 infrastructure code to support RapidIO interconnect devices.
2144
2145source "drivers/rapidio/Kconfig"
2146
2147endmenu
2148
2149
2150menu "Executable file formats / Emulations"
2151
2152source "fs/Kconfig.binfmt"
2153
2154config IA32_EMULATION
2155 bool "IA32 Emulation"
2156 depends on X86_64
2157 select COMPAT_BINFMT_ELF
2158 ---help---
2159 Include code to run legacy 32-bit programs under a
2160 64-bit kernel. You should likely turn this on, unless you're
2161 100% sure that you don't have any 32-bit programs left.
2162
2163config IA32_AOUT
2164 tristate "IA32 a.out support"
2165 depends on IA32_EMULATION
2166 ---help---
2167 Support old a.out binaries in the 32bit emulation.
2168
2169config X86_X32
2170 bool "x32 ABI for 64-bit mode (EXPERIMENTAL)"
2171 depends on X86_64 && IA32_EMULATION && EXPERIMENTAL
2172 ---help---
2173 Include code to run binaries for the x32 native 32-bit ABI
2174 for 64-bit processors. An x32 process gets access to the
2175 full 64-bit register file and wide data path while leaving
2176 pointers at 32 bits for smaller memory footprint.
2177
2178 You will need a recent binutils (2.22 or later) with
2179 elf32_x86_64 support enabled to compile a kernel with this
2180 option set.
2181
2182config COMPAT
2183 def_bool y
2184 depends on IA32_EMULATION || X86_X32
2185 select ARCH_WANT_OLD_COMPAT_IPC
2186
2187config COMPAT_FOR_U64_ALIGNMENT
2188 def_bool COMPAT
2189 depends on X86_64
2190
2191config SYSVIPC_COMPAT
2192 def_bool y
2193 depends on COMPAT && SYSVIPC
2194
2195config KEYS_COMPAT
2196 bool
2197 depends on COMPAT && KEYS
2198 default y
2199
2200endmenu
2201
2202
2203config HAVE_ATOMIC_IOMAP
2204 def_bool y
2205 depends on X86_32
2206
2207config HAVE_TEXT_POKE_SMP
2208 bool
2209 select STOP_MACHINE if SMP
2210
2211config X86_DEV_DMA_OPS
2212 bool
2213 depends on X86_64 || STA2X11
2214
2215config X86_DMA_REMAP
2216 bool
2217 depends on STA2X11
2218
2219source "net/Kconfig"
2220
2221source "drivers/Kconfig"
2222
2223source "drivers/firmware/Kconfig"
2224
2225source "fs/Kconfig"
2226
2227source "arch/x86/Kconfig.debug"
2228
2229source "security/Kconfig"
2230
2231source "crypto/Kconfig"
2232
2233source "arch/x86/kvm/Kconfig"
2234
2235source "lib/Kconfig"
1# SPDX-License-Identifier: GPL-2.0
2# Select 32 or 64 bit
3config 64BIT
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
6 help
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
9
10config X86_32
11 def_bool y
12 depends on !64BIT
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
15 select CLKSRC_I8253
16 select CLONE_BACKWARDS
17 select GENERIC_VDSO_32
18 select HAVE_DEBUG_STACKOVERFLOW
19 select KMAP_LOCAL
20 select MODULES_USE_ELF_REL
21 select OLD_SIGACTION
22 select ARCH_SPLIT_ARG64
23
24config X86_64
25 def_bool y
26 depends on 64BIT
27 # Options that are inherently 64-bit kernel only:
28 select ARCH_HAS_GIGANTIC_PAGE
29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30 select ARCH_SUPPORTS_PER_VMA_LOCK
31 select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE
32 select HAVE_ARCH_SOFT_DIRTY
33 select MODULES_USE_ELF_RELA
34 select NEED_DMA_MAP_STATE
35 select SWIOTLB
36 select ARCH_HAS_ELFCORE_COMPAT
37 select ZONE_DMA32
38 select EXECMEM if DYNAMIC_FTRACE
39
40config FORCE_DYNAMIC_FTRACE
41 def_bool y
42 depends on X86_32
43 depends on FUNCTION_TRACER
44 select DYNAMIC_FTRACE
45 help
46 We keep the static function tracing (!DYNAMIC_FTRACE) around
47 in order to test the non static function tracing in the
48 generic code, as other architectures still use it. But we
49 only need to keep it around for x86_64. No need to keep it
50 for x86_32. For x86_32, force DYNAMIC_FTRACE.
51#
52# Arch settings
53#
54# ( Note that options that are marked 'if X86_64' could in principle be
55# ported to 32-bit as well. )
56#
57config X86
58 def_bool y
59 #
60 # Note: keep this list sorted alphabetically
61 #
62 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
63 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
64 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU
65 select ARCH_32BIT_OFF_T if X86_32
66 select ARCH_CLOCKSOURCE_INIT
67 select ARCH_CONFIGURES_CPU_MITIGATIONS
68 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
69 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
70 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
71 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
72 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
73 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
74 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
75 select ARCH_HAS_CACHE_LINE_SIZE
76 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
77 select ARCH_HAS_CPU_FINALIZE_INIT
78 select ARCH_HAS_CPU_PASID if IOMMU_SVA
79 select ARCH_HAS_CURRENT_STACK_POINTER
80 select ARCH_HAS_DEBUG_VIRTUAL
81 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
82 select ARCH_HAS_DEVMEM_IS_ALLOWED
83 select ARCH_HAS_DMA_OPS if GART_IOMMU || XEN
84 select ARCH_HAS_EARLY_DEBUG if KGDB
85 select ARCH_HAS_ELF_RANDOMIZE
86 select ARCH_HAS_FAST_MULTIPLIER
87 select ARCH_HAS_FORTIFY_SOURCE
88 select ARCH_HAS_GCOV_PROFILE_ALL
89 select ARCH_HAS_KCOV if X86_64
90 select ARCH_HAS_KERNEL_FPU_SUPPORT
91 select ARCH_HAS_MEM_ENCRYPT
92 select ARCH_HAS_MEMBARRIER_SYNC_CORE
93 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
94 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
95 select ARCH_HAS_PMEM_API if X86_64
96 select ARCH_HAS_PREEMPT_LAZY
97 select ARCH_HAS_PTE_DEVMAP if X86_64
98 select ARCH_HAS_PTE_SPECIAL
99 select ARCH_HAS_HW_PTE_YOUNG
100 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
101 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
102 select ARCH_HAS_COPY_MC if X86_64
103 select ARCH_HAS_SET_MEMORY
104 select ARCH_HAS_SET_DIRECT_MAP
105 select ARCH_HAS_STRICT_KERNEL_RWX
106 select ARCH_HAS_STRICT_MODULE_RWX
107 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
108 select ARCH_HAS_SYSCALL_WRAPPER
109 select ARCH_HAS_UBSAN
110 select ARCH_HAS_DEBUG_WX
111 select ARCH_HAS_ZONE_DMA_SET if EXPERT
112 select ARCH_HAVE_NMI_SAFE_CMPXCHG
113 select ARCH_HAVE_EXTRA_ELF_NOTES
114 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
115 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
116 select ARCH_MIGHT_HAVE_PC_PARPORT
117 select ARCH_MIGHT_HAVE_PC_SERIO
118 select ARCH_STACKWALK
119 select ARCH_SUPPORTS_ACPI
120 select ARCH_SUPPORTS_ATOMIC_RMW
121 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
122 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
123 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
124 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
125 select ARCH_SUPPORTS_CFI_CLANG if X86_64
126 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
127 select ARCH_SUPPORTS_LTO_CLANG
128 select ARCH_SUPPORTS_LTO_CLANG_THIN
129 select ARCH_SUPPORTS_RT
130 select ARCH_SUPPORTS_AUTOFDO_CLANG
131 select ARCH_SUPPORTS_PROPELLER_CLANG if X86_64
132 select ARCH_USE_BUILTIN_BSWAP
133 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64
134 select ARCH_USE_MEMTEST
135 select ARCH_USE_QUEUED_RWLOCKS
136 select ARCH_USE_QUEUED_SPINLOCKS
137 select ARCH_USE_SYM_ANNOTATIONS
138 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
139 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
140 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
141 select ARCH_WANTS_NO_INSTR
142 select ARCH_WANT_GENERAL_HUGETLB
143 select ARCH_WANT_HUGE_PMD_SHARE
144 select ARCH_WANT_LD_ORPHAN_WARN
145 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64
146 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64
147 select ARCH_WANTS_THP_SWAP if X86_64
148 select ARCH_HAS_PARANOID_L1D_FLUSH
149 select BUILDTIME_TABLE_SORT
150 select CLKEVT_I8253
151 select CLOCKSOURCE_WATCHDOG
152 # Word-size accesses may read uninitialized data past the trailing \0
153 # in strings and cause false KMSAN reports.
154 select DCACHE_WORD_ACCESS if !KMSAN
155 select DYNAMIC_SIGFRAME
156 select EDAC_ATOMIC_SCRUB
157 select EDAC_SUPPORT
158 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
159 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST
160 select GENERIC_CLOCKEVENTS_MIN_ADJUST
161 select GENERIC_CMOS_UPDATE
162 select GENERIC_CPU_AUTOPROBE
163 select GENERIC_CPU_DEVICES
164 select GENERIC_CPU_VULNERABILITIES
165 select GENERIC_EARLY_IOREMAP
166 select GENERIC_ENTRY
167 select GENERIC_IOMAP
168 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
169 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
170 select GENERIC_IRQ_MIGRATION if SMP
171 select GENERIC_IRQ_PROBE
172 select GENERIC_IRQ_RESERVATION_MODE
173 select GENERIC_IRQ_SHOW
174 select GENERIC_PENDING_IRQ if SMP
175 select GENERIC_PTDUMP
176 select GENERIC_SMP_IDLE_THREAD
177 select GENERIC_TIME_VSYSCALL
178 select GENERIC_GETTIMEOFDAY
179 select GENERIC_VDSO_TIME_NS
180 select GENERIC_VDSO_OVERFLOW_PROTECT
181 select GUP_GET_PXX_LOW_HIGH if X86_PAE
182 select HARDIRQS_SW_RESEND
183 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
184 select HAS_IOPORT
185 select HAVE_ACPI_APEI if ACPI
186 select HAVE_ACPI_APEI_NMI if ACPI
187 select HAVE_ALIGNED_STRUCT_PAGE
188 select HAVE_ARCH_AUDITSYSCALL
189 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
190 select HAVE_ARCH_HUGE_VMALLOC if X86_64
191 select HAVE_ARCH_JUMP_LABEL
192 select HAVE_ARCH_JUMP_LABEL_RELATIVE
193 select HAVE_ARCH_KASAN if X86_64
194 select HAVE_ARCH_KASAN_VMALLOC if X86_64
195 select HAVE_ARCH_KFENCE
196 select HAVE_ARCH_KMSAN if X86_64
197 select HAVE_ARCH_KGDB
198 select HAVE_ARCH_MMAP_RND_BITS if MMU
199 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
200 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
201 select HAVE_ARCH_PREL32_RELOCATIONS
202 select HAVE_ARCH_SECCOMP_FILTER
203 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
204 select HAVE_ARCH_STACKLEAK
205 select HAVE_ARCH_TRACEHOOK
206 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
207 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
208 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
209 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
210 select HAVE_ARCH_VMAP_STACK if X86_64
211 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
212 select HAVE_ARCH_WITHIN_STACK_FRAMES
213 select HAVE_ASM_MODVERSIONS
214 select HAVE_CMPXCHG_DOUBLE
215 select HAVE_CMPXCHG_LOCAL
216 select HAVE_CONTEXT_TRACKING_USER if X86_64
217 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
218 select HAVE_C_RECORDMCOUNT
219 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
220 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
221 select HAVE_BUILDTIME_MCOUNT_SORT
222 select HAVE_DEBUG_KMEMLEAK
223 select HAVE_DMA_CONTIGUOUS
224 select HAVE_DYNAMIC_FTRACE
225 select HAVE_DYNAMIC_FTRACE_WITH_REGS
226 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
227 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
228 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
229 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
230 select HAVE_EBPF_JIT
231 select HAVE_EFFICIENT_UNALIGNED_ACCESS
232 select HAVE_EISA
233 select HAVE_EXIT_THREAD
234 select HAVE_GUP_FAST
235 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
236 select HAVE_FTRACE_MCOUNT_RECORD
237 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
238 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
239 select HAVE_FUNCTION_TRACER
240 select HAVE_GCC_PLUGINS
241 select HAVE_HW_BREAKPOINT
242 select HAVE_IOREMAP_PROT
243 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
244 select HAVE_IRQ_TIME_ACCOUNTING
245 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
246 select HAVE_KERNEL_BZIP2
247 select HAVE_KERNEL_GZIP
248 select HAVE_KERNEL_LZ4
249 select HAVE_KERNEL_LZMA
250 select HAVE_KERNEL_LZO
251 select HAVE_KERNEL_XZ
252 select HAVE_KERNEL_ZSTD
253 select HAVE_KPROBES
254 select HAVE_KPROBES_ON_FTRACE
255 select HAVE_FUNCTION_ERROR_INJECTION
256 select HAVE_KRETPROBES
257 select HAVE_RETHOOK
258 select HAVE_LIVEPATCH if X86_64
259 select HAVE_MIXED_BREAKPOINTS_REGS
260 select HAVE_MOD_ARCH_SPECIFIC
261 select HAVE_MOVE_PMD
262 select HAVE_MOVE_PUD
263 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
264 select HAVE_NMI
265 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
266 select HAVE_OBJTOOL if X86_64
267 select HAVE_OPTPROBES
268 select HAVE_PAGE_SIZE_4KB
269 select HAVE_PCSPKR_PLATFORM
270 select HAVE_PERF_EVENTS
271 select HAVE_PERF_EVENTS_NMI
272 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
273 select HAVE_PCI
274 select HAVE_PERF_REGS
275 select HAVE_PERF_USER_STACK_DUMP
276 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
277 select MMU_GATHER_MERGE_VMAS
278 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
279 select HAVE_REGS_AND_STACK_ACCESS_API
280 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
281 select HAVE_FUNCTION_ARG_ACCESS_API
282 select HAVE_SETUP_PER_CPU_AREA
283 select HAVE_SOFTIRQ_ON_OWN_STACK
284 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
285 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
286 select HAVE_STATIC_CALL
287 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
288 select HAVE_PREEMPT_DYNAMIC_CALL
289 select HAVE_RSEQ
290 select HAVE_RUST if X86_64
291 select HAVE_SYSCALL_TRACEPOINTS
292 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
293 select HAVE_UNSTABLE_SCHED_CLOCK
294 select HAVE_USER_RETURN_NOTIFIER
295 select HAVE_GENERIC_VDSO
296 select VDSO_GETRANDOM if X86_64
297 select HOTPLUG_PARALLEL if SMP && X86_64
298 select HOTPLUG_SMT if SMP
299 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32
300 select IRQ_FORCED_THREADING
301 select LOCK_MM_AND_FIND_VMA
302 select NEED_PER_CPU_EMBED_FIRST_CHUNK
303 select NEED_PER_CPU_PAGE_FIRST_CHUNK
304 select NEED_SG_DMA_LENGTH
305 select NUMA_MEMBLKS if NUMA
306 select PCI_DOMAINS if PCI
307 select PCI_LOCKLESS_CONFIG if PCI
308 select PERF_EVENTS
309 select RTC_LIB
310 select RTC_MC146818_LIB
311 select SPARSE_IRQ
312 select SYSCTL_EXCEPTION_TRACE
313 select THREAD_INFO_IN_TASK
314 select TRACE_IRQFLAGS_SUPPORT
315 select TRACE_IRQFLAGS_NMI_SUPPORT
316 select USER_STACKTRACE_SUPPORT
317 select HAVE_ARCH_KCSAN if X86_64
318 select PROC_PID_ARCH_STATUS if PROC_FS
319 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
320 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16
321 select FUNCTION_ALIGNMENT_4B
322 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
323 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
324
325config INSTRUCTION_DECODER
326 def_bool y
327 depends on KPROBES || PERF_EVENTS || UPROBES
328
329config OUTPUT_FORMAT
330 string
331 default "elf32-i386" if X86_32
332 default "elf64-x86-64" if X86_64
333
334config LOCKDEP_SUPPORT
335 def_bool y
336
337config STACKTRACE_SUPPORT
338 def_bool y
339
340config MMU
341 def_bool y
342
343config ARCH_MMAP_RND_BITS_MIN
344 default 28 if 64BIT
345 default 8
346
347config ARCH_MMAP_RND_BITS_MAX
348 default 32 if 64BIT
349 default 16
350
351config ARCH_MMAP_RND_COMPAT_BITS_MIN
352 default 8
353
354config ARCH_MMAP_RND_COMPAT_BITS_MAX
355 default 16
356
357config SBUS
358 bool
359
360config GENERIC_ISA_DMA
361 def_bool y
362 depends on ISA_DMA_API
363
364config GENERIC_CSUM
365 bool
366 default y if KMSAN || KASAN
367
368config GENERIC_BUG
369 def_bool y
370 depends on BUG
371 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
372
373config GENERIC_BUG_RELATIVE_POINTERS
374 bool
375
376config ARCH_MAY_HAVE_PC_FDC
377 def_bool y
378 depends on ISA_DMA_API
379
380config GENERIC_CALIBRATE_DELAY
381 def_bool y
382
383config ARCH_HAS_CPU_RELAX
384 def_bool y
385
386config ARCH_HIBERNATION_POSSIBLE
387 def_bool y
388
389config ARCH_SUSPEND_POSSIBLE
390 def_bool y
391
392config AUDIT_ARCH
393 def_bool y if X86_64
394
395config KASAN_SHADOW_OFFSET
396 hex
397 depends on KASAN
398 default 0xdffffc0000000000
399
400config HAVE_INTEL_TXT
401 def_bool y
402 depends on INTEL_IOMMU && ACPI
403
404config X86_64_SMP
405 def_bool y
406 depends on X86_64 && SMP
407
408config ARCH_SUPPORTS_UPROBES
409 def_bool y
410
411config FIX_EARLYCON_MEM
412 def_bool y
413
414config DYNAMIC_PHYSICAL_MASK
415 bool
416
417config PGTABLE_LEVELS
418 int
419 default 5 if X86_5LEVEL
420 default 4 if X86_64
421 default 3 if X86_PAE
422 default 2
423
424config CC_HAS_SANE_STACKPROTECTOR
425 bool
426 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
427 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
428 help
429 We have to make sure stack protector is unconditionally disabled if
430 the compiler produces broken code or if it does not let us control
431 the segment on 32-bit kernels.
432
433menu "Processor type and features"
434
435config SMP
436 bool "Symmetric multi-processing support"
437 help
438 This enables support for systems with more than one CPU. If you have
439 a system with only one CPU, say N. If you have a system with more
440 than one CPU, say Y.
441
442 If you say N here, the kernel will run on uni- and multiprocessor
443 machines, but will use only one CPU of a multiprocessor machine. If
444 you say Y here, the kernel will run on many, but not all,
445 uniprocessor machines. On a uniprocessor machine, the kernel
446 will run faster if you say N here.
447
448 Note that if you say Y here and choose architecture "586" or
449 "Pentium" under "Processor family", the kernel will not work on 486
450 architectures. Similarly, multiprocessor kernels for the "PPro"
451 architecture may not work on all Pentium based boards.
452
453 People using multiprocessor machines who say Y here should also say
454 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
455 Management" code will be disabled if you say Y here.
456
457 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
458 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
459 <http://www.tldp.org/docs.html#howto>.
460
461 If you don't know what to do here, say N.
462
463config X86_X2APIC
464 bool "Support x2apic"
465 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
466 help
467 This enables x2apic support on CPUs that have this feature.
468
469 This allows 32-bit apic IDs (so it can support very large systems),
470 and accesses the local apic via MSRs not via mmio.
471
472 Some Intel systems circa 2022 and later are locked into x2APIC mode
473 and can not fall back to the legacy APIC modes if SGX or TDX are
474 enabled in the BIOS. They will boot with very reduced functionality
475 without enabling this option.
476
477 If you don't know what to do here, say N.
478
479config X86_POSTED_MSI
480 bool "Enable MSI and MSI-x delivery by posted interrupts"
481 depends on X86_64 && IRQ_REMAP
482 help
483 This enables MSIs that are under interrupt remapping to be delivered as
484 posted interrupts to the host kernel. Interrupt throughput can
485 potentially be improved by coalescing CPU notifications during high
486 frequency bursts.
487
488 If you don't know what to do here, say N.
489
490config X86_MPPARSE
491 bool "Enable MPS table" if ACPI
492 default y
493 depends on X86_LOCAL_APIC
494 help
495 For old smp systems that do not have proper acpi support. Newer systems
496 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
497
498config X86_CPU_RESCTRL
499 bool "x86 CPU resource control support"
500 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
501 select KERNFS
502 select PROC_CPU_RESCTRL if PROC_FS
503 help
504 Enable x86 CPU resource control support.
505
506 Provide support for the allocation and monitoring of system resources
507 usage by the CPU.
508
509 Intel calls this Intel Resource Director Technology
510 (Intel(R) RDT). More information about RDT can be found in the
511 Intel x86 Architecture Software Developer Manual.
512
513 AMD calls this AMD Platform Quality of Service (AMD QoS).
514 More information about AMD QoS can be found in the AMD64 Technology
515 Platform Quality of Service Extensions manual.
516
517 Say N if unsure.
518
519config X86_FRED
520 bool "Flexible Return and Event Delivery"
521 depends on X86_64
522 help
523 When enabled, try to use Flexible Return and Event Delivery
524 instead of the legacy SYSCALL/SYSENTER/IDT architecture for
525 ring transitions and exception/interrupt handling if the
526 system supports it.
527
528config X86_BIGSMP
529 bool "Support for big SMP systems with more than 8 CPUs"
530 depends on SMP && X86_32
531 help
532 This option is needed for the systems that have more than 8 CPUs.
533
534config X86_EXTENDED_PLATFORM
535 bool "Support for extended (non-PC) x86 platforms"
536 default y
537 help
538 If you disable this option then the kernel will only support
539 standard PC platforms. (which covers the vast majority of
540 systems out there.)
541
542 If you enable this option then you'll be able to select support
543 for the following non-PC x86 platforms, depending on the value of
544 CONFIG_64BIT.
545
546 32-bit platforms (CONFIG_64BIT=n):
547 Goldfish (Android emulator)
548 AMD Elan
549 RDC R-321x SoC
550 SGI 320/540 (Visual Workstation)
551 STA2X11-based (e.g. Northville)
552 Moorestown MID devices
553
554 64-bit platforms (CONFIG_64BIT=y):
555 Numascale NumaChip
556 ScaleMP vSMP
557 SGI Ultraviolet
558
559 If you have one of these systems, or if you want to build a
560 generic distribution kernel, say Y here - otherwise say N.
561
562# This is an alphabetically sorted list of 64 bit extended platforms
563# Please maintain the alphabetic order if and when there are additions
564config X86_NUMACHIP
565 bool "Numascale NumaChip"
566 depends on X86_64
567 depends on X86_EXTENDED_PLATFORM
568 depends on NUMA
569 depends on SMP
570 depends on X86_X2APIC
571 depends on PCI_MMCONFIG
572 help
573 Adds support for Numascale NumaChip large-SMP systems. Needed to
574 enable more than ~168 cores.
575 If you don't have one of these, you should say N here.
576
577config X86_VSMP
578 bool "ScaleMP vSMP"
579 select HYPERVISOR_GUEST
580 select PARAVIRT
581 depends on X86_64 && PCI
582 depends on X86_EXTENDED_PLATFORM
583 depends on SMP
584 help
585 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
586 supposed to run on these EM64T-based machines. Only choose this option
587 if you have one of these machines.
588
589config X86_UV
590 bool "SGI Ultraviolet"
591 depends on X86_64
592 depends on X86_EXTENDED_PLATFORM
593 depends on NUMA
594 depends on EFI
595 depends on KEXEC_CORE
596 depends on X86_X2APIC
597 depends on PCI
598 help
599 This option is needed in order to support SGI Ultraviolet systems.
600 If you don't have one of these, you should say N here.
601
602# Following is an alphabetically sorted list of 32 bit extended platforms
603# Please maintain the alphabetic order if and when there are additions
604
605config X86_GOLDFISH
606 bool "Goldfish (Virtual Platform)"
607 depends on X86_EXTENDED_PLATFORM
608 help
609 Enable support for the Goldfish virtual platform used primarily
610 for Android development. Unless you are building for the Android
611 Goldfish emulator say N here.
612
613config X86_INTEL_CE
614 bool "CE4100 TV platform"
615 depends on PCI
616 depends on PCI_GODIRECT
617 depends on X86_IO_APIC
618 depends on X86_32
619 depends on X86_EXTENDED_PLATFORM
620 select X86_REBOOTFIXUPS
621 select OF
622 select OF_EARLY_FLATTREE
623 help
624 Select for the Intel CE media processor (CE4100) SOC.
625 This option compiles in support for the CE4100 SOC for settop
626 boxes and media devices.
627
628config X86_INTEL_MID
629 bool "Intel MID platform support"
630 depends on X86_EXTENDED_PLATFORM
631 depends on X86_PLATFORM_DEVICES
632 depends on PCI
633 depends on X86_64 || (PCI_GOANY && X86_32)
634 depends on X86_IO_APIC
635 select I2C
636 select DW_APB_TIMER
637 select INTEL_SCU_PCI
638 help
639 Select to build a kernel capable of supporting Intel MID (Mobile
640 Internet Device) platform systems which do not have the PCI legacy
641 interfaces. If you are building for a PC class system say N here.
642
643 Intel MID platforms are based on an Intel processor and chipset which
644 consume less power than most of the x86 derivatives.
645
646config X86_INTEL_QUARK
647 bool "Intel Quark platform support"
648 depends on X86_32
649 depends on X86_EXTENDED_PLATFORM
650 depends on X86_PLATFORM_DEVICES
651 depends on X86_TSC
652 depends on PCI
653 depends on PCI_GOANY
654 depends on X86_IO_APIC
655 select IOSF_MBI
656 select INTEL_IMR
657 select COMMON_CLK
658 help
659 Select to include support for Quark X1000 SoC.
660 Say Y here if you have a Quark based system such as the Arduino
661 compatible Intel Galileo.
662
663config X86_INTEL_LPSS
664 bool "Intel Low Power Subsystem Support"
665 depends on X86 && ACPI && PCI
666 select COMMON_CLK
667 select PINCTRL
668 select IOSF_MBI
669 help
670 Select to build support for Intel Low Power Subsystem such as
671 found on Intel Lynxpoint PCH. Selecting this option enables
672 things like clock tree (common clock framework) and pincontrol
673 which are needed by the LPSS peripheral drivers.
674
675config X86_AMD_PLATFORM_DEVICE
676 bool "AMD ACPI2Platform devices support"
677 depends on ACPI
678 select COMMON_CLK
679 select PINCTRL
680 help
681 Select to interpret AMD specific ACPI device to platform device
682 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
683 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
684 implemented under PINCTRL subsystem.
685
686config IOSF_MBI
687 tristate "Intel SoC IOSF Sideband support for SoC platforms"
688 depends on PCI
689 help
690 This option enables sideband register access support for Intel SoC
691 platforms. On these platforms the IOSF sideband is used in lieu of
692 MSR's for some register accesses, mostly but not limited to thermal
693 and power. Drivers may query the availability of this device to
694 determine if they need the sideband in order to work on these
695 platforms. The sideband is available on the following SoC products.
696 This list is not meant to be exclusive.
697 - BayTrail
698 - Braswell
699 - Quark
700
701 You should say Y if you are running a kernel on one of these SoC's.
702
703config IOSF_MBI_DEBUG
704 bool "Enable IOSF sideband access through debugfs"
705 depends on IOSF_MBI && DEBUG_FS
706 help
707 Select this option to expose the IOSF sideband access registers (MCR,
708 MDR, MCRX) through debugfs to write and read register information from
709 different units on the SoC. This is most useful for obtaining device
710 state information for debug and analysis. As this is a general access
711 mechanism, users of this option would have specific knowledge of the
712 device they want to access.
713
714 If you don't require the option or are in doubt, say N.
715
716config X86_RDC321X
717 bool "RDC R-321x SoC"
718 depends on X86_32
719 depends on X86_EXTENDED_PLATFORM
720 select M486
721 select X86_REBOOTFIXUPS
722 help
723 This option is needed for RDC R-321x system-on-chip, also known
724 as R-8610-(G).
725 If you don't have one of these chips, you should say N here.
726
727config X86_32_NON_STANDARD
728 bool "Support non-standard 32-bit SMP architectures"
729 depends on X86_32 && SMP
730 depends on X86_EXTENDED_PLATFORM
731 help
732 This option compiles in the bigsmp and STA2X11 default
733 subarchitectures. It is intended for a generic binary
734 kernel. If you select them all, kernel will probe it one by
735 one and will fallback to default.
736
737# Alphabetically sorted list of Non standard 32 bit platforms
738
739config X86_SUPPORTS_MEMORY_FAILURE
740 def_bool y
741 # MCE code calls memory_failure():
742 depends on X86_MCE
743 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
744 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
745 depends on X86_64 || !SPARSEMEM
746 select ARCH_SUPPORTS_MEMORY_FAILURE
747
748config STA2X11
749 bool "STA2X11 Companion Chip Support"
750 depends on X86_32_NON_STANDARD && PCI
751 select SWIOTLB
752 select MFD_STA2X11
753 select GPIOLIB
754 help
755 This adds support for boards based on the STA2X11 IO-Hub,
756 a.k.a. "ConneXt". The chip is used in place of the standard
757 PC chipset, so all "standard" peripherals are missing. If this
758 option is selected the kernel will still be able to boot on
759 standard PC machines.
760
761config X86_32_IRIS
762 tristate "Eurobraille/Iris poweroff module"
763 depends on X86_32
764 help
765 The Iris machines from EuroBraille do not have APM or ACPI support
766 to shut themselves down properly. A special I/O sequence is
767 needed to do so, which is what this module does at
768 kernel shutdown.
769
770 This is only for Iris machines from EuroBraille.
771
772 If unused, say N.
773
774config SCHED_OMIT_FRAME_POINTER
775 def_bool y
776 prompt "Single-depth WCHAN output"
777 depends on X86
778 help
779 Calculate simpler /proc/<PID>/wchan values. If this option
780 is disabled then wchan values will recurse back to the
781 caller function. This provides more accurate wchan values,
782 at the expense of slightly more scheduling overhead.
783
784 If in doubt, say "Y".
785
786menuconfig HYPERVISOR_GUEST
787 bool "Linux guest support"
788 help
789 Say Y here to enable options for running Linux under various hyper-
790 visors. This option enables basic hypervisor detection and platform
791 setup.
792
793 If you say N, all options in this submenu will be skipped and
794 disabled, and Linux guest support won't be built in.
795
796if HYPERVISOR_GUEST
797
798config PARAVIRT
799 bool "Enable paravirtualization code"
800 depends on HAVE_STATIC_CALL
801 help
802 This changes the kernel so it can modify itself when it is run
803 under a hypervisor, potentially improving performance significantly
804 over full virtualization. However, when run without a hypervisor
805 the kernel is theoretically slower and slightly larger.
806
807config PARAVIRT_XXL
808 bool
809
810config PARAVIRT_DEBUG
811 bool "paravirt-ops debugging"
812 depends on PARAVIRT && DEBUG_KERNEL
813 help
814 Enable to debug paravirt_ops internals. Specifically, BUG if
815 a paravirt_op is missing when it is called.
816
817config PARAVIRT_SPINLOCKS
818 bool "Paravirtualization layer for spinlocks"
819 depends on PARAVIRT && SMP
820 help
821 Paravirtualized spinlocks allow a pvops backend to replace the
822 spinlock implementation with something virtualization-friendly
823 (for example, block the virtual CPU rather than spinning).
824
825 It has a minimal impact on native kernels and gives a nice performance
826 benefit on paravirtualized KVM / Xen kernels.
827
828 If you are unsure how to answer this question, answer Y.
829
830config X86_HV_CALLBACK_VECTOR
831 def_bool n
832
833source "arch/x86/xen/Kconfig"
834
835config KVM_GUEST
836 bool "KVM Guest support (including kvmclock)"
837 depends on PARAVIRT
838 select PARAVIRT_CLOCK
839 select ARCH_CPUIDLE_HALTPOLL
840 select X86_HV_CALLBACK_VECTOR
841 default y
842 help
843 This option enables various optimizations for running under the KVM
844 hypervisor. It includes a paravirtualized clock, so that instead
845 of relying on a PIT (or probably other) emulation by the
846 underlying device model, the host provides the guest with
847 timing infrastructure such as time of day, and system time
848
849config ARCH_CPUIDLE_HALTPOLL
850 def_bool n
851 prompt "Disable host haltpoll when loading haltpoll driver"
852 help
853 If virtualized under KVM, disable host haltpoll.
854
855config PVH
856 bool "Support for running PVH guests"
857 help
858 This option enables the PVH entry point for guest virtual machines
859 as specified in the x86/HVM direct boot ABI.
860
861config PARAVIRT_TIME_ACCOUNTING
862 bool "Paravirtual steal time accounting"
863 depends on PARAVIRT
864 help
865 Select this option to enable fine granularity task steal time
866 accounting. Time spent executing other tasks in parallel with
867 the current vCPU is discounted from the vCPU power. To account for
868 that, there can be a small performance impact.
869
870 If in doubt, say N here.
871
872config PARAVIRT_CLOCK
873 bool
874
875config JAILHOUSE_GUEST
876 bool "Jailhouse non-root cell support"
877 depends on X86_64 && PCI
878 select X86_PM_TIMER
879 help
880 This option allows to run Linux as guest in a Jailhouse non-root
881 cell. You can leave this option disabled if you only want to start
882 Jailhouse and run Linux afterwards in the root cell.
883
884config ACRN_GUEST
885 bool "ACRN Guest support"
886 depends on X86_64
887 select X86_HV_CALLBACK_VECTOR
888 help
889 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
890 a flexible, lightweight reference open-source hypervisor, built with
891 real-time and safety-criticality in mind. It is built for embedded
892 IOT with small footprint and real-time features. More details can be
893 found in https://projectacrn.org/.
894
895config INTEL_TDX_GUEST
896 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
897 depends on X86_64 && CPU_SUP_INTEL
898 depends on X86_X2APIC
899 depends on EFI_STUB
900 select ARCH_HAS_CC_PLATFORM
901 select X86_MEM_ENCRYPT
902 select X86_MCE
903 select UNACCEPTED_MEMORY
904 help
905 Support running as a guest under Intel TDX. Without this support,
906 the guest kernel can not boot or run under TDX.
907 TDX includes memory encryption and integrity capabilities
908 which protect the confidentiality and integrity of guest
909 memory contents and CPU state. TDX guests are protected from
910 some attacks from the VMM.
911
912endif # HYPERVISOR_GUEST
913
914source "arch/x86/Kconfig.cpu"
915
916config HPET_TIMER
917 def_bool X86_64
918 prompt "HPET Timer Support" if X86_32
919 help
920 Use the IA-PC HPET (High Precision Event Timer) to manage
921 time in preference to the PIT and RTC, if a HPET is
922 present.
923 HPET is the next generation timer replacing legacy 8254s.
924 The HPET provides a stable time base on SMP
925 systems, unlike the TSC, but it is more expensive to access,
926 as it is off-chip. The interface used is documented
927 in the HPET spec, revision 1.
928
929 You can safely choose Y here. However, HPET will only be
930 activated if the platform and the BIOS support this feature.
931 Otherwise the 8254 will be used for timing services.
932
933 Choose N to continue using the legacy 8254 timer.
934
935config HPET_EMULATE_RTC
936 def_bool y
937 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
938
939# Mark as expert because too many people got it wrong.
940# The code disables itself when not needed.
941config DMI
942 default y
943 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
944 bool "Enable DMI scanning" if EXPERT
945 help
946 Enabled scanning of DMI to identify machine quirks. Say Y
947 here unless you have verified that your setup is not
948 affected by entries in the DMI blacklist. Required by PNP
949 BIOS code.
950
951config GART_IOMMU
952 bool "Old AMD GART IOMMU support"
953 select IOMMU_HELPER
954 select SWIOTLB
955 depends on X86_64 && PCI && AMD_NB
956 help
957 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
958 GART based hardware IOMMUs.
959
960 The GART supports full DMA access for devices with 32-bit access
961 limitations, on systems with more than 3 GB. This is usually needed
962 for USB, sound, many IDE/SATA chipsets and some other devices.
963
964 Newer systems typically have a modern AMD IOMMU, supported via
965 the CONFIG_AMD_IOMMU=y config option.
966
967 In normal configurations this driver is only active when needed:
968 there's more than 3 GB of memory and the system contains a
969 32-bit limited device.
970
971 If unsure, say Y.
972
973config BOOT_VESA_SUPPORT
974 bool
975 help
976 If true, at least one selected framebuffer driver can take advantage
977 of VESA video modes set at an early boot stage via the vga= parameter.
978
979config MAXSMP
980 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
981 depends on X86_64 && SMP && DEBUG_KERNEL
982 select CPUMASK_OFFSTACK
983 help
984 Enable maximum number of CPUS and NUMA Nodes for this architecture.
985 If unsure, say N.
986
987#
988# The maximum number of CPUs supported:
989#
990# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
991# and which can be configured interactively in the
992# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
993#
994# The ranges are different on 32-bit and 64-bit kernels, depending on
995# hardware capabilities and scalability features of the kernel.
996#
997# ( If MAXSMP is enabled we just use the highest possible value and disable
998# interactive configuration. )
999#
1000
1001config NR_CPUS_RANGE_BEGIN
1002 int
1003 default NR_CPUS_RANGE_END if MAXSMP
1004 default 1 if !SMP
1005 default 2
1006
1007config NR_CPUS_RANGE_END
1008 int
1009 depends on X86_32
1010 default 64 if SMP && X86_BIGSMP
1011 default 8 if SMP && !X86_BIGSMP
1012 default 1 if !SMP
1013
1014config NR_CPUS_RANGE_END
1015 int
1016 depends on X86_64
1017 default 8192 if SMP && CPUMASK_OFFSTACK
1018 default 512 if SMP && !CPUMASK_OFFSTACK
1019 default 1 if !SMP
1020
1021config NR_CPUS_DEFAULT
1022 int
1023 depends on X86_32
1024 default 32 if X86_BIGSMP
1025 default 8 if SMP
1026 default 1 if !SMP
1027
1028config NR_CPUS_DEFAULT
1029 int
1030 depends on X86_64
1031 default 8192 if MAXSMP
1032 default 64 if SMP
1033 default 1 if !SMP
1034
1035config NR_CPUS
1036 int "Maximum number of CPUs" if SMP && !MAXSMP
1037 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1038 default NR_CPUS_DEFAULT
1039 help
1040 This allows you to specify the maximum number of CPUs which this
1041 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1042 supported value is 8192, otherwise the maximum value is 512. The
1043 minimum value which makes sense is 2.
1044
1045 This is purely to save memory: each supported CPU adds about 8KB
1046 to the kernel image.
1047
1048config SCHED_CLUSTER
1049 bool "Cluster scheduler support"
1050 depends on SMP
1051 default y
1052 help
1053 Cluster scheduler support improves the CPU scheduler's decision
1054 making when dealing with machines that have clusters of CPUs.
1055 Cluster usually means a couple of CPUs which are placed closely
1056 by sharing mid-level caches, last-level cache tags or internal
1057 busses.
1058
1059config SCHED_SMT
1060 def_bool y if SMP
1061
1062config SCHED_MC
1063 def_bool y
1064 prompt "Multi-core scheduler support"
1065 depends on SMP
1066 help
1067 Multi-core scheduler support improves the CPU scheduler's decision
1068 making when dealing with multi-core CPU chips at a cost of slightly
1069 increased overhead in some places. If unsure say N here.
1070
1071config SCHED_MC_PRIO
1072 bool "CPU core priorities scheduler support"
1073 depends on SCHED_MC
1074 select X86_INTEL_PSTATE if CPU_SUP_INTEL
1075 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI
1076 select CPU_FREQ
1077 default y
1078 help
1079 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1080 core ordering determined at manufacturing time, which allows
1081 certain cores to reach higher turbo frequencies (when running
1082 single threaded workloads) than others.
1083
1084 Enabling this kernel feature teaches the scheduler about
1085 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1086 scheduler's CPU selection logic accordingly, so that higher
1087 overall system performance can be achieved.
1088
1089 This feature will have no effect on CPUs without this feature.
1090
1091 If unsure say Y here.
1092
1093config UP_LATE_INIT
1094 def_bool y
1095 depends on !SMP && X86_LOCAL_APIC
1096
1097config X86_UP_APIC
1098 bool "Local APIC support on uniprocessors" if !PCI_MSI
1099 default PCI_MSI
1100 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1101 help
1102 A local APIC (Advanced Programmable Interrupt Controller) is an
1103 integrated interrupt controller in the CPU. If you have a single-CPU
1104 system which has a processor with a local APIC, you can say Y here to
1105 enable and use it. If you say Y here even though your machine doesn't
1106 have a local APIC, then the kernel will still run with no slowdown at
1107 all. The local APIC supports CPU-generated self-interrupts (timer,
1108 performance counters), and the NMI watchdog which detects hard
1109 lockups.
1110
1111config X86_UP_IOAPIC
1112 bool "IO-APIC support on uniprocessors"
1113 depends on X86_UP_APIC
1114 help
1115 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1116 SMP-capable replacement for PC-style interrupt controllers. Most
1117 SMP systems and many recent uniprocessor systems have one.
1118
1119 If you have a single-CPU system with an IO-APIC, you can say Y here
1120 to use it. If you say Y here even though your machine doesn't have
1121 an IO-APIC, then the kernel will still run with no slowdown at all.
1122
1123config X86_LOCAL_APIC
1124 def_bool y
1125 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1126 select IRQ_DOMAIN_HIERARCHY
1127
1128config ACPI_MADT_WAKEUP
1129 def_bool y
1130 depends on X86_64
1131 depends on ACPI
1132 depends on SMP
1133 depends on X86_LOCAL_APIC
1134
1135config X86_IO_APIC
1136 def_bool y
1137 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1138
1139config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1140 bool "Reroute for broken boot IRQs"
1141 depends on X86_IO_APIC
1142 help
1143 This option enables a workaround that fixes a source of
1144 spurious interrupts. This is recommended when threaded
1145 interrupt handling is used on systems where the generation of
1146 superfluous "boot interrupts" cannot be disabled.
1147
1148 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1149 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1150 kernel does during interrupt handling). On chipsets where this
1151 boot IRQ generation cannot be disabled, this workaround keeps
1152 the original IRQ line masked so that only the equivalent "boot
1153 IRQ" is delivered to the CPUs. The workaround also tells the
1154 kernel to set up the IRQ handler on the boot IRQ line. In this
1155 way only one interrupt is delivered to the kernel. Otherwise
1156 the spurious second interrupt may cause the kernel to bring
1157 down (vital) interrupt lines.
1158
1159 Only affects "broken" chipsets. Interrupt sharing may be
1160 increased on these systems.
1161
1162config X86_MCE
1163 bool "Machine Check / overheating reporting"
1164 select GENERIC_ALLOCATOR
1165 default y
1166 help
1167 Machine Check support allows the processor to notify the
1168 kernel if it detects a problem (e.g. overheating, data corruption).
1169 The action the kernel takes depends on the severity of the problem,
1170 ranging from warning messages to halting the machine.
1171
1172config X86_MCELOG_LEGACY
1173 bool "Support for deprecated /dev/mcelog character device"
1174 depends on X86_MCE
1175 help
1176 Enable support for /dev/mcelog which is needed by the old mcelog
1177 userspace logging daemon. Consider switching to the new generation
1178 rasdaemon solution.
1179
1180config X86_MCE_INTEL
1181 def_bool y
1182 prompt "Intel MCE features"
1183 depends on X86_MCE && X86_LOCAL_APIC
1184 help
1185 Additional support for intel specific MCE features such as
1186 the thermal monitor.
1187
1188config X86_MCE_AMD
1189 def_bool y
1190 prompt "AMD MCE features"
1191 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1192 help
1193 Additional support for AMD specific MCE features such as
1194 the DRAM Error Threshold.
1195
1196config X86_ANCIENT_MCE
1197 bool "Support for old Pentium 5 / WinChip machine checks"
1198 depends on X86_32 && X86_MCE
1199 help
1200 Include support for machine check handling on old Pentium 5 or WinChip
1201 systems. These typically need to be enabled explicitly on the command
1202 line.
1203
1204config X86_MCE_THRESHOLD
1205 depends on X86_MCE_AMD || X86_MCE_INTEL
1206 def_bool y
1207
1208config X86_MCE_INJECT
1209 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1210 tristate "Machine check injector support"
1211 help
1212 Provide support for injecting machine checks for testing purposes.
1213 If you don't know what a machine check is and you don't do kernel
1214 QA it is safe to say n.
1215
1216source "arch/x86/events/Kconfig"
1217
1218config X86_LEGACY_VM86
1219 bool "Legacy VM86 support"
1220 depends on X86_32
1221 help
1222 This option allows user programs to put the CPU into V8086
1223 mode, which is an 80286-era approximation of 16-bit real mode.
1224
1225 Some very old versions of X and/or vbetool require this option
1226 for user mode setting. Similarly, DOSEMU will use it if
1227 available to accelerate real mode DOS programs. However, any
1228 recent version of DOSEMU, X, or vbetool should be fully
1229 functional even without kernel VM86 support, as they will all
1230 fall back to software emulation. Nevertheless, if you are using
1231 a 16-bit DOS program where 16-bit performance matters, vm86
1232 mode might be faster than emulation and you might want to
1233 enable this option.
1234
1235 Note that any app that works on a 64-bit kernel is unlikely to
1236 need this option, as 64-bit kernels don't, and can't, support
1237 V8086 mode. This option is also unrelated to 16-bit protected
1238 mode and is not needed to run most 16-bit programs under Wine.
1239
1240 Enabling this option increases the complexity of the kernel
1241 and slows down exception handling a tiny bit.
1242
1243 If unsure, say N here.
1244
1245config VM86
1246 bool
1247 default X86_LEGACY_VM86
1248
1249config X86_16BIT
1250 bool "Enable support for 16-bit segments" if EXPERT
1251 default y
1252 depends on MODIFY_LDT_SYSCALL
1253 help
1254 This option is required by programs like Wine to run 16-bit
1255 protected mode legacy code on x86 processors. Disabling
1256 this option saves about 300 bytes on i386, or around 6K text
1257 plus 16K runtime memory on x86-64,
1258
1259config X86_ESPFIX32
1260 def_bool y
1261 depends on X86_16BIT && X86_32
1262
1263config X86_ESPFIX64
1264 def_bool y
1265 depends on X86_16BIT && X86_64
1266
1267config X86_VSYSCALL_EMULATION
1268 bool "Enable vsyscall emulation" if EXPERT
1269 default y
1270 depends on X86_64
1271 help
1272 This enables emulation of the legacy vsyscall page. Disabling
1273 it is roughly equivalent to booting with vsyscall=none, except
1274 that it will also disable the helpful warning if a program
1275 tries to use a vsyscall. With this option set to N, offending
1276 programs will just segfault, citing addresses of the form
1277 0xffffffffff600?00.
1278
1279 This option is required by many programs built before 2013, and
1280 care should be used even with newer programs if set to N.
1281
1282 Disabling this option saves about 7K of kernel size and
1283 possibly 4K of additional runtime pagetable memory.
1284
1285config X86_IOPL_IOPERM
1286 bool "IOPERM and IOPL Emulation"
1287 default y
1288 help
1289 This enables the ioperm() and iopl() syscalls which are necessary
1290 for legacy applications.
1291
1292 Legacy IOPL support is an overbroad mechanism which allows user
1293 space aside of accessing all 65536 I/O ports also to disable
1294 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1295 capabilities and permission from potentially active security
1296 modules.
1297
1298 The emulation restricts the functionality of the syscall to
1299 only allowing the full range I/O port access, but prevents the
1300 ability to disable interrupts from user space which would be
1301 granted if the hardware IOPL mechanism would be used.
1302
1303config TOSHIBA
1304 tristate "Toshiba Laptop support"
1305 depends on X86_32
1306 help
1307 This adds a driver to safely access the System Management Mode of
1308 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1309 not work on models with a Phoenix BIOS. The System Management Mode
1310 is used to set the BIOS and power saving options on Toshiba portables.
1311
1312 For information on utilities to make use of this driver see the
1313 Toshiba Linux utilities web site at:
1314 <http://www.buzzard.org.uk/toshiba/>.
1315
1316 Say Y if you intend to run this kernel on a Toshiba portable.
1317 Say N otherwise.
1318
1319config X86_REBOOTFIXUPS
1320 bool "Enable X86 board specific fixups for reboot"
1321 depends on X86_32
1322 help
1323 This enables chipset and/or board specific fixups to be done
1324 in order to get reboot to work correctly. This is only needed on
1325 some combinations of hardware and BIOS. The symptom, for which
1326 this config is intended, is when reboot ends with a stalled/hung
1327 system.
1328
1329 Currently, the only fixup is for the Geode machines using
1330 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1331
1332 Say Y if you want to enable the fixup. Currently, it's safe to
1333 enable this option even if you don't need it.
1334 Say N otherwise.
1335
1336config MICROCODE
1337 def_bool y
1338 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1339 select CRYPTO_LIB_SHA256 if CPU_SUP_AMD
1340
1341config MICROCODE_INITRD32
1342 def_bool y
1343 depends on MICROCODE && X86_32 && BLK_DEV_INITRD
1344
1345config MICROCODE_LATE_LOADING
1346 bool "Late microcode loading (DANGEROUS)"
1347 default n
1348 depends on MICROCODE && SMP
1349 help
1350 Loading microcode late, when the system is up and executing instructions
1351 is a tricky business and should be avoided if possible. Just the sequence
1352 of synchronizing all cores and SMT threads is one fragile dance which does
1353 not guarantee that cores might not softlock after the loading. Therefore,
1354 use this at your own risk. Late loading taints the kernel unless the
1355 microcode header indicates that it is safe for late loading via the
1356 minimal revision check. This minimal revision check can be enforced on
1357 the kernel command line with "microcode.minrev=Y".
1358
1359config MICROCODE_LATE_FORCE_MINREV
1360 bool "Enforce late microcode loading minimal revision check"
1361 default n
1362 depends on MICROCODE_LATE_LOADING
1363 help
1364 To prevent that users load microcode late which modifies already
1365 in use features, newer microcode patches have a minimum revision field
1366 in the microcode header, which tells the kernel which minimum
1367 revision must be active in the CPU to safely load that new microcode
1368 late into the running system. If disabled the check will not
1369 be enforced but the kernel will be tainted when the minimal
1370 revision check fails.
1371
1372 This minimal revision check can also be controlled via the
1373 "microcode.minrev" parameter on the kernel command line.
1374
1375 If unsure say Y.
1376
1377config X86_MSR
1378 tristate "/dev/cpu/*/msr - Model-specific register support"
1379 help
1380 This device gives privileged processes access to the x86
1381 Model-Specific Registers (MSRs). It is a character device with
1382 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1383 MSR accesses are directed to a specific CPU on multi-processor
1384 systems.
1385
1386config X86_CPUID
1387 tristate "/dev/cpu/*/cpuid - CPU information support"
1388 help
1389 This device gives processes access to the x86 CPUID instruction to
1390 be executed on a specific processor. It is a character device
1391 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1392 /dev/cpu/31/cpuid.
1393
1394choice
1395 prompt "High Memory Support"
1396 default HIGHMEM4G
1397 depends on X86_32
1398
1399config NOHIGHMEM
1400 bool "off"
1401 help
1402 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1403 However, the address space of 32-bit x86 processors is only 4
1404 Gigabytes large. That means that, if you have a large amount of
1405 physical memory, not all of it can be "permanently mapped" by the
1406 kernel. The physical memory that's not permanently mapped is called
1407 "high memory".
1408
1409 If you are compiling a kernel which will never run on a machine with
1410 more than 1 Gigabyte total physical RAM, answer "off" here (default
1411 choice and suitable for most users). This will result in a "3GB/1GB"
1412 split: 3GB are mapped so that each process sees a 3GB virtual memory
1413 space and the remaining part of the 4GB virtual memory space is used
1414 by the kernel to permanently map as much physical memory as
1415 possible.
1416
1417 If the machine has between 1 and 4 Gigabytes physical RAM, then
1418 answer "4GB" here.
1419
1420 If more than 4 Gigabytes is used then answer "64GB" here. This
1421 selection turns Intel PAE (Physical Address Extension) mode on.
1422 PAE implements 3-level paging on IA32 processors. PAE is fully
1423 supported by Linux, PAE mode is implemented on all recent Intel
1424 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1425 then the kernel will not boot on CPUs that don't support PAE!
1426
1427 The actual amount of total physical memory will either be
1428 auto detected or can be forced by using a kernel command line option
1429 such as "mem=256M". (Try "man bootparam" or see the documentation of
1430 your boot loader (lilo or loadlin) about how to pass options to the
1431 kernel at boot time.)
1432
1433 If unsure, say "off".
1434
1435config HIGHMEM4G
1436 bool "4GB"
1437 help
1438 Select this if you have a 32-bit processor and between 1 and 4
1439 gigabytes of physical RAM.
1440
1441config HIGHMEM64G
1442 bool "64GB"
1443 depends on X86_HAVE_PAE
1444 select X86_PAE
1445 help
1446 Select this if you have a 32-bit processor and more than 4
1447 gigabytes of physical RAM.
1448
1449endchoice
1450
1451choice
1452 prompt "Memory split" if EXPERT
1453 default VMSPLIT_3G
1454 depends on X86_32
1455 help
1456 Select the desired split between kernel and user memory.
1457
1458 If the address range available to the kernel is less than the
1459 physical memory installed, the remaining memory will be available
1460 as "high memory". Accessing high memory is a little more costly
1461 than low memory, as it needs to be mapped into the kernel first.
1462 Note that increasing the kernel address space limits the range
1463 available to user programs, making the address space there
1464 tighter. Selecting anything other than the default 3G/1G split
1465 will also likely make your kernel incompatible with binary-only
1466 kernel modules.
1467
1468 If you are not absolutely sure what you are doing, leave this
1469 option alone!
1470
1471 config VMSPLIT_3G
1472 bool "3G/1G user/kernel split"
1473 config VMSPLIT_3G_OPT
1474 depends on !X86_PAE
1475 bool "3G/1G user/kernel split (for full 1G low memory)"
1476 config VMSPLIT_2G
1477 bool "2G/2G user/kernel split"
1478 config VMSPLIT_2G_OPT
1479 depends on !X86_PAE
1480 bool "2G/2G user/kernel split (for full 2G low memory)"
1481 config VMSPLIT_1G
1482 bool "1G/3G user/kernel split"
1483endchoice
1484
1485config PAGE_OFFSET
1486 hex
1487 default 0xB0000000 if VMSPLIT_3G_OPT
1488 default 0x80000000 if VMSPLIT_2G
1489 default 0x78000000 if VMSPLIT_2G_OPT
1490 default 0x40000000 if VMSPLIT_1G
1491 default 0xC0000000
1492 depends on X86_32
1493
1494config HIGHMEM
1495 def_bool y
1496 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1497
1498config X86_PAE
1499 bool "PAE (Physical Address Extension) Support"
1500 depends on X86_32 && X86_HAVE_PAE
1501 select PHYS_ADDR_T_64BIT
1502 select SWIOTLB
1503 help
1504 PAE is required for NX support, and furthermore enables
1505 larger swapspace support for non-overcommit purposes. It
1506 has the cost of more pagetable lookup overhead, and also
1507 consumes more pagetable space per process.
1508
1509config X86_5LEVEL
1510 bool "Enable 5-level page tables support"
1511 default y
1512 select DYNAMIC_MEMORY_LAYOUT
1513 select SPARSEMEM_VMEMMAP
1514 depends on X86_64
1515 help
1516 5-level paging enables access to larger address space:
1517 up to 128 PiB of virtual address space and 4 PiB of
1518 physical address space.
1519
1520 It will be supported by future Intel CPUs.
1521
1522 A kernel with the option enabled can be booted on machines that
1523 support 4- or 5-level paging.
1524
1525 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1526 information.
1527
1528 Say N if unsure.
1529
1530config X86_DIRECT_GBPAGES
1531 def_bool y
1532 depends on X86_64
1533 help
1534 Certain kernel features effectively disable kernel
1535 linear 1 GB mappings (even if the CPU otherwise
1536 supports them), so don't confuse the user by printing
1537 that we have them enabled.
1538
1539config X86_CPA_STATISTICS
1540 bool "Enable statistic for Change Page Attribute"
1541 depends on DEBUG_FS
1542 help
1543 Expose statistics about the Change Page Attribute mechanism, which
1544 helps to determine the effectiveness of preserving large and huge
1545 page mappings when mapping protections are changed.
1546
1547config X86_MEM_ENCRYPT
1548 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1549 select DYNAMIC_PHYSICAL_MASK
1550 def_bool n
1551
1552config AMD_MEM_ENCRYPT
1553 bool "AMD Secure Memory Encryption (SME) support"
1554 depends on X86_64 && CPU_SUP_AMD
1555 depends on EFI_STUB
1556 select DMA_COHERENT_POOL
1557 select ARCH_USE_MEMREMAP_PROT
1558 select INSTRUCTION_DECODER
1559 select ARCH_HAS_CC_PLATFORM
1560 select X86_MEM_ENCRYPT
1561 select UNACCEPTED_MEMORY
1562 help
1563 Say yes to enable support for the encryption of system memory.
1564 This requires an AMD processor that supports Secure Memory
1565 Encryption (SME).
1566
1567# Common NUMA Features
1568config NUMA
1569 bool "NUMA Memory Allocation and Scheduler Support"
1570 depends on SMP
1571 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1572 default y if X86_BIGSMP
1573 select USE_PERCPU_NUMA_NODE_ID
1574 select OF_NUMA if OF
1575 help
1576 Enable NUMA (Non-Uniform Memory Access) support.
1577
1578 The kernel will try to allocate memory used by a CPU on the
1579 local memory controller of the CPU and add some more
1580 NUMA awareness to the kernel.
1581
1582 For 64-bit this is recommended if the system is Intel Core i7
1583 (or later), AMD Opteron, or EM64T NUMA.
1584
1585 For 32-bit this is only needed if you boot a 32-bit
1586 kernel on a 64-bit NUMA platform.
1587
1588 Otherwise, you should say N.
1589
1590config AMD_NUMA
1591 def_bool y
1592 prompt "Old style AMD Opteron NUMA detection"
1593 depends on X86_64 && NUMA && PCI
1594 help
1595 Enable AMD NUMA node topology detection. You should say Y here if
1596 you have a multi processor AMD system. This uses an old method to
1597 read the NUMA configuration directly from the builtin Northbridge
1598 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1599 which also takes priority if both are compiled in.
1600
1601config X86_64_ACPI_NUMA
1602 def_bool y
1603 prompt "ACPI NUMA detection"
1604 depends on X86_64 && NUMA && ACPI && PCI
1605 select ACPI_NUMA
1606 help
1607 Enable ACPI SRAT based node topology detection.
1608
1609config NODES_SHIFT
1610 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1611 range 1 10
1612 default "10" if MAXSMP
1613 default "6" if X86_64
1614 default "3"
1615 depends on NUMA
1616 help
1617 Specify the maximum number of NUMA Nodes available on the target
1618 system. Increases memory reserved to accommodate various tables.
1619
1620config ARCH_FLATMEM_ENABLE
1621 def_bool y
1622 depends on X86_32 && !NUMA
1623
1624config ARCH_SPARSEMEM_ENABLE
1625 def_bool y
1626 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1627 select SPARSEMEM_STATIC if X86_32
1628 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1629
1630config ARCH_SPARSEMEM_DEFAULT
1631 def_bool X86_64 || (NUMA && X86_32)
1632
1633config ARCH_SELECT_MEMORY_MODEL
1634 def_bool y
1635 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1636
1637config ARCH_MEMORY_PROBE
1638 bool "Enable sysfs memory/probe interface"
1639 depends on MEMORY_HOTPLUG
1640 help
1641 This option enables a sysfs memory/probe interface for testing.
1642 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1643 If you are unsure how to answer this question, answer N.
1644
1645config ARCH_PROC_KCORE_TEXT
1646 def_bool y
1647 depends on X86_64 && PROC_KCORE
1648
1649config ILLEGAL_POINTER_VALUE
1650 hex
1651 default 0 if X86_32
1652 default 0xdead000000000000 if X86_64
1653
1654config X86_PMEM_LEGACY_DEVICE
1655 bool
1656
1657config X86_PMEM_LEGACY
1658 tristate "Support non-standard NVDIMMs and ADR protected memory"
1659 depends on PHYS_ADDR_T_64BIT
1660 depends on BLK_DEV
1661 select X86_PMEM_LEGACY_DEVICE
1662 select NUMA_KEEP_MEMINFO if NUMA
1663 select LIBNVDIMM
1664 help
1665 Treat memory marked using the non-standard e820 type of 12 as used
1666 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1667 The kernel will offer these regions to the 'pmem' driver so
1668 they can be used for persistent storage.
1669
1670 Say Y if unsure.
1671
1672config HIGHPTE
1673 bool "Allocate 3rd-level pagetables from highmem"
1674 depends on HIGHMEM
1675 help
1676 The VM uses one page table entry for each page of physical memory.
1677 For systems with a lot of RAM, this can be wasteful of precious
1678 low memory. Setting this option will put user-space page table
1679 entries in high memory.
1680
1681config X86_CHECK_BIOS_CORRUPTION
1682 bool "Check for low memory corruption"
1683 help
1684 Periodically check for memory corruption in low memory, which
1685 is suspected to be caused by BIOS. Even when enabled in the
1686 configuration, it is disabled at runtime. Enable it by
1687 setting "memory_corruption_check=1" on the kernel command
1688 line. By default it scans the low 64k of memory every 60
1689 seconds; see the memory_corruption_check_size and
1690 memory_corruption_check_period parameters in
1691 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1692
1693 When enabled with the default parameters, this option has
1694 almost no overhead, as it reserves a relatively small amount
1695 of memory and scans it infrequently. It both detects corruption
1696 and prevents it from affecting the running system.
1697
1698 It is, however, intended as a diagnostic tool; if repeatable
1699 BIOS-originated corruption always affects the same memory,
1700 you can use memmap= to prevent the kernel from using that
1701 memory.
1702
1703config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1704 bool "Set the default setting of memory_corruption_check"
1705 depends on X86_CHECK_BIOS_CORRUPTION
1706 default y
1707 help
1708 Set whether the default state of memory_corruption_check is
1709 on or off.
1710
1711config MATH_EMULATION
1712 bool
1713 depends on MODIFY_LDT_SYSCALL
1714 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1715 help
1716 Linux can emulate a math coprocessor (used for floating point
1717 operations) if you don't have one. 486DX and Pentium processors have
1718 a math coprocessor built in, 486SX and 386 do not, unless you added
1719 a 487DX or 387, respectively. (The messages during boot time can
1720 give you some hints here ["man dmesg"].) Everyone needs either a
1721 coprocessor or this emulation.
1722
1723 If you don't have a math coprocessor, you need to say Y here; if you
1724 say Y here even though you have a coprocessor, the coprocessor will
1725 be used nevertheless. (This behavior can be changed with the kernel
1726 command line option "no387", which comes handy if your coprocessor
1727 is broken. Try "man bootparam" or see the documentation of your boot
1728 loader (lilo or loadlin) about how to pass options to the kernel at
1729 boot time.) This means that it is a good idea to say Y here if you
1730 intend to use this kernel on different machines.
1731
1732 More information about the internals of the Linux math coprocessor
1733 emulation can be found in <file:arch/x86/math-emu/README>.
1734
1735 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1736 kernel, it won't hurt.
1737
1738config MTRR
1739 def_bool y
1740 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1741 help
1742 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1743 the Memory Type Range Registers (MTRRs) may be used to control
1744 processor access to memory ranges. This is most useful if you have
1745 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1746 allows bus write transfers to be combined into a larger transfer
1747 before bursting over the PCI/AGP bus. This can increase performance
1748 of image write operations 2.5 times or more. Saying Y here creates a
1749 /proc/mtrr file which may be used to manipulate your processor's
1750 MTRRs. Typically the X server should use this.
1751
1752 This code has a reasonably generic interface so that similar
1753 control registers on other processors can be easily supported
1754 as well:
1755
1756 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1757 Registers (ARRs) which provide a similar functionality to MTRRs. For
1758 these, the ARRs are used to emulate the MTRRs.
1759 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1760 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1761 write-combining. All of these processors are supported by this code
1762 and it makes sense to say Y here if you have one of them.
1763
1764 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1765 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1766 can lead to all sorts of problems, so it's good to say Y here.
1767
1768 You can safely say Y even if your machine doesn't have MTRRs, you'll
1769 just add about 9 KB to your kernel.
1770
1771 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1772
1773config MTRR_SANITIZER
1774 def_bool y
1775 prompt "MTRR cleanup support"
1776 depends on MTRR
1777 help
1778 Convert MTRR layout from continuous to discrete, so X drivers can
1779 add writeback entries.
1780
1781 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1782 The largest mtrr entry size for a continuous block can be set with
1783 mtrr_chunk_size.
1784
1785 If unsure, say Y.
1786
1787config MTRR_SANITIZER_ENABLE_DEFAULT
1788 int "MTRR cleanup enable value (0-1)"
1789 range 0 1
1790 default "0"
1791 depends on MTRR_SANITIZER
1792 help
1793 Enable mtrr cleanup default value
1794
1795config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1796 int "MTRR cleanup spare reg num (0-7)"
1797 range 0 7
1798 default "1"
1799 depends on MTRR_SANITIZER
1800 help
1801 mtrr cleanup spare entries default, it can be changed via
1802 mtrr_spare_reg_nr=N on the kernel command line.
1803
1804config X86_PAT
1805 def_bool y
1806 prompt "x86 PAT support" if EXPERT
1807 depends on MTRR
1808 select ARCH_USES_PG_ARCH_2
1809 help
1810 Use PAT attributes to setup page level cache control.
1811
1812 PATs are the modern equivalents of MTRRs and are much more
1813 flexible than MTRRs.
1814
1815 Say N here if you see bootup problems (boot crash, boot hang,
1816 spontaneous reboots) or a non-working video driver.
1817
1818 If unsure, say Y.
1819
1820config X86_UMIP
1821 def_bool y
1822 prompt "User Mode Instruction Prevention" if EXPERT
1823 help
1824 User Mode Instruction Prevention (UMIP) is a security feature in
1825 some x86 processors. If enabled, a general protection fault is
1826 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1827 executed in user mode. These instructions unnecessarily expose
1828 information about the hardware state.
1829
1830 The vast majority of applications do not use these instructions.
1831 For the very few that do, software emulation is provided in
1832 specific cases in protected and virtual-8086 modes. Emulated
1833 results are dummy.
1834
1835config CC_HAS_IBT
1836 # GCC >= 9 and binutils >= 2.29
1837 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1838 # Clang/LLVM >= 14
1839 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1840 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1841 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1842 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1843 $(as-instr,endbr64)
1844
1845config X86_CET
1846 def_bool n
1847 help
1848 CET features configured (Shadow stack or IBT)
1849
1850config X86_KERNEL_IBT
1851 prompt "Indirect Branch Tracking"
1852 def_bool y
1853 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1854 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1855 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1856 select OBJTOOL
1857 select X86_CET
1858 help
1859 Build the kernel with support for Indirect Branch Tracking, a
1860 hardware support course-grain forward-edge Control Flow Integrity
1861 protection. It enforces that all indirect calls must land on
1862 an ENDBR instruction, as such, the compiler will instrument the
1863 code with them to make this happen.
1864
1865 In addition to building the kernel with IBT, seal all functions that
1866 are not indirect call targets, avoiding them ever becoming one.
1867
1868 This requires LTO like objtool runs and will slow down the build. It
1869 does significantly reduce the number of ENDBR instructions in the
1870 kernel image.
1871
1872config X86_INTEL_MEMORY_PROTECTION_KEYS
1873 prompt "Memory Protection Keys"
1874 def_bool y
1875 # Note: only available in 64-bit mode
1876 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1877 select ARCH_USES_HIGH_VMA_FLAGS
1878 select ARCH_HAS_PKEYS
1879 help
1880 Memory Protection Keys provides a mechanism for enforcing
1881 page-based protections, but without requiring modification of the
1882 page tables when an application changes protection domains.
1883
1884 For details, see Documentation/core-api/protection-keys.rst
1885
1886 If unsure, say y.
1887
1888config ARCH_PKEY_BITS
1889 int
1890 default 4
1891
1892choice
1893 prompt "TSX enable mode"
1894 depends on CPU_SUP_INTEL
1895 default X86_INTEL_TSX_MODE_OFF
1896 help
1897 Intel's TSX (Transactional Synchronization Extensions) feature
1898 allows to optimize locking protocols through lock elision which
1899 can lead to a noticeable performance boost.
1900
1901 On the other hand it has been shown that TSX can be exploited
1902 to form side channel attacks (e.g. TAA) and chances are there
1903 will be more of those attacks discovered in the future.
1904
1905 Therefore TSX is not enabled by default (aka tsx=off). An admin
1906 might override this decision by tsx=on the command line parameter.
1907 Even with TSX enabled, the kernel will attempt to enable the best
1908 possible TAA mitigation setting depending on the microcode available
1909 for the particular machine.
1910
1911 This option allows to set the default tsx mode between tsx=on, =off
1912 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1913 details.
1914
1915 Say off if not sure, auto if TSX is in use but it should be used on safe
1916 platforms or on if TSX is in use and the security aspect of tsx is not
1917 relevant.
1918
1919config X86_INTEL_TSX_MODE_OFF
1920 bool "off"
1921 help
1922 TSX is disabled if possible - equals to tsx=off command line parameter.
1923
1924config X86_INTEL_TSX_MODE_ON
1925 bool "on"
1926 help
1927 TSX is always enabled on TSX capable HW - equals the tsx=on command
1928 line parameter.
1929
1930config X86_INTEL_TSX_MODE_AUTO
1931 bool "auto"
1932 help
1933 TSX is enabled on TSX capable HW that is believed to be safe against
1934 side channel attacks- equals the tsx=auto command line parameter.
1935endchoice
1936
1937config X86_SGX
1938 bool "Software Guard eXtensions (SGX)"
1939 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1940 depends on CRYPTO=y
1941 depends on CRYPTO_SHA256=y
1942 select MMU_NOTIFIER
1943 select NUMA_KEEP_MEMINFO if NUMA
1944 select XARRAY_MULTI
1945 help
1946 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1947 that can be used by applications to set aside private regions of code
1948 and data, referred to as enclaves. An enclave's private memory can
1949 only be accessed by code running within the enclave. Accesses from
1950 outside the enclave, including other enclaves, are disallowed by
1951 hardware.
1952
1953 If unsure, say N.
1954
1955config X86_USER_SHADOW_STACK
1956 bool "X86 userspace shadow stack"
1957 depends on AS_WRUSS
1958 depends on X86_64
1959 select ARCH_USES_HIGH_VMA_FLAGS
1960 select ARCH_HAS_USER_SHADOW_STACK
1961 select X86_CET
1962 help
1963 Shadow stack protection is a hardware feature that detects function
1964 return address corruption. This helps mitigate ROP attacks.
1965 Applications must be enabled to use it, and old userspace does not
1966 get protection "for free".
1967
1968 CPUs supporting shadow stacks were first released in 2020.
1969
1970 See Documentation/arch/x86/shstk.rst for more information.
1971
1972 If unsure, say N.
1973
1974config INTEL_TDX_HOST
1975 bool "Intel Trust Domain Extensions (TDX) host support"
1976 depends on CPU_SUP_INTEL
1977 depends on X86_64
1978 depends on KVM_INTEL
1979 depends on X86_X2APIC
1980 select ARCH_KEEP_MEMBLOCK
1981 depends on CONTIG_ALLOC
1982 depends on !KEXEC_CORE
1983 depends on X86_MCE
1984 help
1985 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
1986 host and certain physical attacks. This option enables necessary TDX
1987 support in the host kernel to run confidential VMs.
1988
1989 If unsure, say N.
1990
1991config EFI
1992 bool "EFI runtime service support"
1993 depends on ACPI
1994 select UCS2_STRING
1995 select EFI_RUNTIME_WRAPPERS
1996 select ARCH_USE_MEMREMAP_PROT
1997 select EFI_RUNTIME_MAP if KEXEC_CORE
1998 help
1999 This enables the kernel to use EFI runtime services that are
2000 available (such as the EFI variable services).
2001
2002 This option is only useful on systems that have EFI firmware.
2003 In addition, you should use the latest ELILO loader available
2004 at <http://elilo.sourceforge.net> in order to take advantage
2005 of EFI runtime services. However, even with this option, the
2006 resultant kernel should continue to boot on existing non-EFI
2007 platforms.
2008
2009config EFI_STUB
2010 bool "EFI stub support"
2011 depends on EFI
2012 select RELOCATABLE
2013 help
2014 This kernel feature allows a bzImage to be loaded directly
2015 by EFI firmware without the use of a bootloader.
2016
2017 See Documentation/admin-guide/efi-stub.rst for more information.
2018
2019config EFI_HANDOVER_PROTOCOL
2020 bool "EFI handover protocol (DEPRECATED)"
2021 depends on EFI_STUB
2022 default y
2023 help
2024 Select this in order to include support for the deprecated EFI
2025 handover protocol, which defines alternative entry points into the
2026 EFI stub. This is a practice that has no basis in the UEFI
2027 specification, and requires a priori knowledge on the part of the
2028 bootloader about Linux/x86 specific ways of passing the command line
2029 and initrd, and where in memory those assets may be loaded.
2030
2031 If in doubt, say Y. Even though the corresponding support is not
2032 present in upstream GRUB or other bootloaders, most distros build
2033 GRUB with numerous downstream patches applied, and may rely on the
2034 handover protocol as as result.
2035
2036config EFI_MIXED
2037 bool "EFI mixed-mode support"
2038 depends on EFI_STUB && X86_64
2039 help
2040 Enabling this feature allows a 64-bit kernel to be booted
2041 on a 32-bit firmware, provided that your CPU supports 64-bit
2042 mode.
2043
2044 Note that it is not possible to boot a mixed-mode enabled
2045 kernel via the EFI boot stub - a bootloader that supports
2046 the EFI handover protocol must be used.
2047
2048 If unsure, say N.
2049
2050config EFI_RUNTIME_MAP
2051 bool "Export EFI runtime maps to sysfs" if EXPERT
2052 depends on EFI
2053 help
2054 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2055 That memory map is required by the 2nd kernel to set up EFI virtual
2056 mappings after kexec, but can also be used for debugging purposes.
2057
2058 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2059
2060source "kernel/Kconfig.hz"
2061
2062config ARCH_SUPPORTS_KEXEC
2063 def_bool y
2064
2065config ARCH_SUPPORTS_KEXEC_FILE
2066 def_bool X86_64
2067
2068config ARCH_SELECTS_KEXEC_FILE
2069 def_bool y
2070 depends on KEXEC_FILE
2071 select HAVE_IMA_KEXEC if IMA
2072
2073config ARCH_SUPPORTS_KEXEC_PURGATORY
2074 def_bool y
2075
2076config ARCH_SUPPORTS_KEXEC_SIG
2077 def_bool y
2078
2079config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2080 def_bool y
2081
2082config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2083 def_bool y
2084
2085config ARCH_SUPPORTS_KEXEC_JUMP
2086 def_bool y
2087
2088config ARCH_SUPPORTS_CRASH_DUMP
2089 def_bool X86_64 || (X86_32 && HIGHMEM)
2090
2091config ARCH_DEFAULT_CRASH_DUMP
2092 def_bool y
2093
2094config ARCH_SUPPORTS_CRASH_HOTPLUG
2095 def_bool y
2096
2097config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
2098 def_bool CRASH_RESERVE
2099
2100config PHYSICAL_START
2101 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2102 default "0x1000000"
2103 help
2104 This gives the physical address where the kernel is loaded.
2105
2106 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage
2107 will decompress itself to above physical address and run from there.
2108 Otherwise, bzImage will run from the address where it has been loaded
2109 by the boot loader. The only exception is if it is loaded below the
2110 above physical address, in which case it will relocate itself there.
2111
2112 In normal kdump cases one does not have to set/change this option
2113 as now bzImage can be compiled as a completely relocatable image
2114 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2115 address. This option is mainly useful for the folks who don't want
2116 to use a bzImage for capturing the crash dump and want to use a
2117 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2118 to be specifically compiled to run from a specific memory area
2119 (normally a reserved region) and this option comes handy.
2120
2121 So if you are using bzImage for capturing the crash dump,
2122 leave the value here unchanged to 0x1000000 and set
2123 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2124 for capturing the crash dump change this value to start of
2125 the reserved region. In other words, it can be set based on
2126 the "X" value as specified in the "crashkernel=YM@XM"
2127 command line boot parameter passed to the panic-ed
2128 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2129 for more details about crash dumps.
2130
2131 Usage of bzImage for capturing the crash dump is recommended as
2132 one does not have to build two kernels. Same kernel can be used
2133 as production kernel and capture kernel. Above option should have
2134 gone away after relocatable bzImage support is introduced. But it
2135 is present because there are users out there who continue to use
2136 vmlinux for dump capture. This option should go away down the
2137 line.
2138
2139 Don't change this unless you know what you are doing.
2140
2141config RELOCATABLE
2142 bool "Build a relocatable kernel"
2143 default y
2144 help
2145 This builds a kernel image that retains relocation information
2146 so it can be loaded someplace besides the default 1MB.
2147 The relocations tend to make the kernel binary about 10% larger,
2148 but are discarded at runtime.
2149
2150 One use is for the kexec on panic case where the recovery kernel
2151 must live at a different physical address than the primary
2152 kernel.
2153
2154 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2155 it has been loaded at and the compile time physical address
2156 (CONFIG_PHYSICAL_START) is used as the minimum location.
2157
2158config RANDOMIZE_BASE
2159 bool "Randomize the address of the kernel image (KASLR)"
2160 depends on RELOCATABLE
2161 default y
2162 help
2163 In support of Kernel Address Space Layout Randomization (KASLR),
2164 this randomizes the physical address at which the kernel image
2165 is decompressed and the virtual address where the kernel
2166 image is mapped, as a security feature that deters exploit
2167 attempts relying on knowledge of the location of kernel
2168 code internals.
2169
2170 On 64-bit, the kernel physical and virtual addresses are
2171 randomized separately. The physical address will be anywhere
2172 between 16MB and the top of physical memory (up to 64TB). The
2173 virtual address will be randomized from 16MB up to 1GB (9 bits
2174 of entropy). Note that this also reduces the memory space
2175 available to kernel modules from 1.5GB to 1GB.
2176
2177 On 32-bit, the kernel physical and virtual addresses are
2178 randomized together. They will be randomized from 16MB up to
2179 512MB (8 bits of entropy).
2180
2181 Entropy is generated using the RDRAND instruction if it is
2182 supported. If RDTSC is supported, its value is mixed into
2183 the entropy pool as well. If neither RDRAND nor RDTSC are
2184 supported, then entropy is read from the i8254 timer. The
2185 usable entropy is limited by the kernel being built using
2186 2GB addressing, and that PHYSICAL_ALIGN must be at a
2187 minimum of 2MB. As a result, only 10 bits of entropy are
2188 theoretically possible, but the implementations are further
2189 limited due to memory layouts.
2190
2191 If unsure, say Y.
2192
2193# Relocation on x86 needs some additional build support
2194config X86_NEED_RELOCS
2195 def_bool y
2196 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2197
2198config PHYSICAL_ALIGN
2199 hex "Alignment value to which kernel should be aligned"
2200 default "0x200000"
2201 range 0x2000 0x1000000 if X86_32
2202 range 0x200000 0x1000000 if X86_64
2203 help
2204 This value puts the alignment restrictions on physical address
2205 where kernel is loaded and run from. Kernel is compiled for an
2206 address which meets above alignment restriction.
2207
2208 If bootloader loads the kernel at a non-aligned address and
2209 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2210 address aligned to above value and run from there.
2211
2212 If bootloader loads the kernel at a non-aligned address and
2213 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2214 load address and decompress itself to the address it has been
2215 compiled for and run from there. The address for which kernel is
2216 compiled already meets above alignment restrictions. Hence the
2217 end result is that kernel runs from a physical address meeting
2218 above alignment restrictions.
2219
2220 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2221 this value must be a multiple of 0x200000.
2222
2223 Don't change this unless you know what you are doing.
2224
2225config DYNAMIC_MEMORY_LAYOUT
2226 bool
2227 help
2228 This option makes base addresses of vmalloc and vmemmap as well as
2229 __PAGE_OFFSET movable during boot.
2230
2231config RANDOMIZE_MEMORY
2232 bool "Randomize the kernel memory sections"
2233 depends on X86_64
2234 depends on RANDOMIZE_BASE
2235 select DYNAMIC_MEMORY_LAYOUT
2236 default RANDOMIZE_BASE
2237 help
2238 Randomizes the base virtual address of kernel memory sections
2239 (physical memory mapping, vmalloc & vmemmap). This security feature
2240 makes exploits relying on predictable memory locations less reliable.
2241
2242 The order of allocations remains unchanged. Entropy is generated in
2243 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2244 configuration have in average 30,000 different possible virtual
2245 addresses for each memory section.
2246
2247 If unsure, say Y.
2248
2249config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2250 hex "Physical memory mapping padding" if EXPERT
2251 depends on RANDOMIZE_MEMORY
2252 default "0xa" if MEMORY_HOTPLUG
2253 default "0x0"
2254 range 0x1 0x40 if MEMORY_HOTPLUG
2255 range 0x0 0x40
2256 help
2257 Define the padding in terabytes added to the existing physical
2258 memory size during kernel memory randomization. It is useful
2259 for memory hotplug support but reduces the entropy available for
2260 address randomization.
2261
2262 If unsure, leave at the default value.
2263
2264config ADDRESS_MASKING
2265 bool "Linear Address Masking support"
2266 depends on X86_64
2267 depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS
2268 help
2269 Linear Address Masking (LAM) modifies the checking that is applied
2270 to 64-bit linear addresses, allowing software to use of the
2271 untranslated address bits for metadata.
2272
2273 The capability can be used for efficient address sanitizers (ASAN)
2274 implementation and for optimizations in JITs.
2275
2276config HOTPLUG_CPU
2277 def_bool y
2278 depends on SMP
2279
2280config COMPAT_VDSO
2281 def_bool n
2282 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2283 depends on COMPAT_32
2284 help
2285 Certain buggy versions of glibc will crash if they are
2286 presented with a 32-bit vDSO that is not mapped at the address
2287 indicated in its segment table.
2288
2289 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2290 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2291 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2292 the only released version with the bug, but OpenSUSE 9
2293 contains a buggy "glibc 2.3.2".
2294
2295 The symptom of the bug is that everything crashes on startup, saying:
2296 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2297
2298 Saying Y here changes the default value of the vdso32 boot
2299 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2300 This works around the glibc bug but hurts performance.
2301
2302 If unsure, say N: if you are compiling your own kernel, you
2303 are unlikely to be using a buggy version of glibc.
2304
2305choice
2306 prompt "vsyscall table for legacy applications"
2307 depends on X86_64
2308 default LEGACY_VSYSCALL_XONLY
2309 help
2310 Legacy user code that does not know how to find the vDSO expects
2311 to be able to issue three syscalls by calling fixed addresses in
2312 kernel space. Since this location is not randomized with ASLR,
2313 it can be used to assist security vulnerability exploitation.
2314
2315 This setting can be changed at boot time via the kernel command
2316 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2317 is deprecated and can only be enabled using the kernel command
2318 line.
2319
2320 On a system with recent enough glibc (2.14 or newer) and no
2321 static binaries, you can say None without a performance penalty
2322 to improve security.
2323
2324 If unsure, select "Emulate execution only".
2325
2326 config LEGACY_VSYSCALL_XONLY
2327 bool "Emulate execution only"
2328 help
2329 The kernel traps and emulates calls into the fixed vsyscall
2330 address mapping and does not allow reads. This
2331 configuration is recommended when userspace might use the
2332 legacy vsyscall area but support for legacy binary
2333 instrumentation of legacy code is not needed. It mitigates
2334 certain uses of the vsyscall area as an ASLR-bypassing
2335 buffer.
2336
2337 config LEGACY_VSYSCALL_NONE
2338 bool "None"
2339 help
2340 There will be no vsyscall mapping at all. This will
2341 eliminate any risk of ASLR bypass due to the vsyscall
2342 fixed address mapping. Attempts to use the vsyscalls
2343 will be reported to dmesg, so that either old or
2344 malicious userspace programs can be identified.
2345
2346endchoice
2347
2348config CMDLINE_BOOL
2349 bool "Built-in kernel command line"
2350 help
2351 Allow for specifying boot arguments to the kernel at
2352 build time. On some systems (e.g. embedded ones), it is
2353 necessary or convenient to provide some or all of the
2354 kernel boot arguments with the kernel itself (that is,
2355 to not rely on the boot loader to provide them.)
2356
2357 To compile command line arguments into the kernel,
2358 set this option to 'Y', then fill in the
2359 boot arguments in CONFIG_CMDLINE.
2360
2361 Systems with fully functional boot loaders (i.e. non-embedded)
2362 should leave this option set to 'N'.
2363
2364config CMDLINE
2365 string "Built-in kernel command string"
2366 depends on CMDLINE_BOOL
2367 default ""
2368 help
2369 Enter arguments here that should be compiled into the kernel
2370 image and used at boot time. If the boot loader provides a
2371 command line at boot time, it is appended to this string to
2372 form the full kernel command line, when the system boots.
2373
2374 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2375 change this behavior.
2376
2377 In most cases, the command line (whether built-in or provided
2378 by the boot loader) should specify the device for the root
2379 file system.
2380
2381config CMDLINE_OVERRIDE
2382 bool "Built-in command line overrides boot loader arguments"
2383 depends on CMDLINE_BOOL && CMDLINE != ""
2384 help
2385 Set this option to 'Y' to have the kernel ignore the boot loader
2386 command line, and use ONLY the built-in command line.
2387
2388 This is used to work around broken boot loaders. This should
2389 be set to 'N' under normal conditions.
2390
2391config MODIFY_LDT_SYSCALL
2392 bool "Enable the LDT (local descriptor table)" if EXPERT
2393 default y
2394 help
2395 Linux can allow user programs to install a per-process x86
2396 Local Descriptor Table (LDT) using the modify_ldt(2) system
2397 call. This is required to run 16-bit or segmented code such as
2398 DOSEMU or some Wine programs. It is also used by some very old
2399 threading libraries.
2400
2401 Enabling this feature adds a small amount of overhead to
2402 context switches and increases the low-level kernel attack
2403 surface. Disabling it removes the modify_ldt(2) system call.
2404
2405 Saying 'N' here may make sense for embedded or server kernels.
2406
2407config STRICT_SIGALTSTACK_SIZE
2408 bool "Enforce strict size checking for sigaltstack"
2409 depends on DYNAMIC_SIGFRAME
2410 help
2411 For historical reasons MINSIGSTKSZ is a constant which became
2412 already too small with AVX512 support. Add a mechanism to
2413 enforce strict checking of the sigaltstack size against the
2414 real size of the FPU frame. This option enables the check
2415 by default. It can also be controlled via the kernel command
2416 line option 'strict_sas_size' independent of this config
2417 switch. Enabling it might break existing applications which
2418 allocate a too small sigaltstack but 'work' because they
2419 never get a signal delivered.
2420
2421 Say 'N' unless you want to really enforce this check.
2422
2423config CFI_AUTO_DEFAULT
2424 bool "Attempt to use FineIBT by default at boot time"
2425 depends on FINEIBT
2426 default y
2427 help
2428 Attempt to use FineIBT by default at boot time. If enabled,
2429 this is the same as booting with "cfi=auto". If disabled,
2430 this is the same as booting with "cfi=kcfi".
2431
2432source "kernel/livepatch/Kconfig"
2433
2434config X86_BUS_LOCK_DETECT
2435 bool "Split Lock Detect and Bus Lock Detect support"
2436 depends on CPU_SUP_INTEL || CPU_SUP_AMD
2437 default y
2438 help
2439 Enable Split Lock Detect and Bus Lock Detect functionalities.
2440 See <file:Documentation/arch/x86/buslock.rst> for more information.
2441
2442endmenu
2443
2444config CC_HAS_NAMED_AS
2445 def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null)
2446 depends on CC_IS_GCC
2447
2448config CC_HAS_NAMED_AS_FIXED_SANITIZERS
2449 def_bool CC_IS_GCC && GCC_VERSION >= 130300
2450
2451config USE_X86_SEG_SUPPORT
2452 def_bool y
2453 depends on CC_HAS_NAMED_AS
2454 #
2455 # -fsanitize=kernel-address (KASAN) and -fsanitize=thread
2456 # (KCSAN) are incompatible with named address spaces with
2457 # GCC < 13.3 - see GCC PR sanitizer/111736.
2458 #
2459 depends on !(KASAN || KCSAN) || CC_HAS_NAMED_AS_FIXED_SANITIZERS
2460
2461config CC_HAS_SLS
2462 def_bool $(cc-option,-mharden-sls=all)
2463
2464config CC_HAS_RETURN_THUNK
2465 def_bool $(cc-option,-mfunction-return=thunk-extern)
2466
2467config CC_HAS_ENTRY_PADDING
2468 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2469
2470config FUNCTION_PADDING_CFI
2471 int
2472 default 59 if FUNCTION_ALIGNMENT_64B
2473 default 27 if FUNCTION_ALIGNMENT_32B
2474 default 11 if FUNCTION_ALIGNMENT_16B
2475 default 3 if FUNCTION_ALIGNMENT_8B
2476 default 0
2477
2478# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2479# except Kconfig can't do arithmetic :/
2480config FUNCTION_PADDING_BYTES
2481 int
2482 default FUNCTION_PADDING_CFI if CFI_CLANG
2483 default FUNCTION_ALIGNMENT
2484
2485config CALL_PADDING
2486 def_bool n
2487 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2488 select FUNCTION_ALIGNMENT_16B
2489
2490config FINEIBT
2491 def_bool y
2492 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE
2493 select CALL_PADDING
2494
2495config HAVE_CALL_THUNKS
2496 def_bool y
2497 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL
2498
2499config CALL_THUNKS
2500 def_bool n
2501 select CALL_PADDING
2502
2503config PREFIX_SYMBOLS
2504 def_bool y
2505 depends on CALL_PADDING && !CFI_CLANG
2506
2507menuconfig CPU_MITIGATIONS
2508 bool "Mitigations for CPU vulnerabilities"
2509 default y
2510 help
2511 Say Y here to enable options which enable mitigations for hardware
2512 vulnerabilities (usually related to speculative execution).
2513 Mitigations can be disabled or restricted to SMT systems at runtime
2514 via the "mitigations" kernel parameter.
2515
2516 If you say N, all mitigations will be disabled. This CANNOT be
2517 overridden at runtime.
2518
2519 Say 'Y', unless you really know what you are doing.
2520
2521if CPU_MITIGATIONS
2522
2523config MITIGATION_PAGE_TABLE_ISOLATION
2524 bool "Remove the kernel mapping in user mode"
2525 default y
2526 depends on (X86_64 || X86_PAE)
2527 help
2528 This feature reduces the number of hardware side channels by
2529 ensuring that the majority of kernel addresses are not mapped
2530 into userspace.
2531
2532 See Documentation/arch/x86/pti.rst for more details.
2533
2534config MITIGATION_RETPOLINE
2535 bool "Avoid speculative indirect branches in kernel"
2536 select OBJTOOL if HAVE_OBJTOOL
2537 default y
2538 help
2539 Compile kernel with the retpoline compiler options to guard against
2540 kernel-to-user data leaks by avoiding speculative indirect
2541 branches. Requires a compiler with -mindirect-branch=thunk-extern
2542 support for full protection. The kernel may run slower.
2543
2544config MITIGATION_RETHUNK
2545 bool "Enable return-thunks"
2546 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK
2547 select OBJTOOL if HAVE_OBJTOOL
2548 default y if X86_64
2549 help
2550 Compile the kernel with the return-thunks compiler option to guard
2551 against kernel-to-user data leaks by avoiding return speculation.
2552 Requires a compiler with -mfunction-return=thunk-extern
2553 support for full protection. The kernel may run slower.
2554
2555config MITIGATION_UNRET_ENTRY
2556 bool "Enable UNRET on kernel entry"
2557 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64
2558 default y
2559 help
2560 Compile the kernel with support for the retbleed=unret mitigation.
2561
2562config MITIGATION_CALL_DEPTH_TRACKING
2563 bool "Mitigate RSB underflow with call depth tracking"
2564 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2565 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2566 select CALL_THUNKS
2567 default y
2568 help
2569 Compile the kernel with call depth tracking to mitigate the Intel
2570 SKL Return-Stack-Buffer (RSB) underflow issue. The mitigation is off
2571 by default and needs to be enabled on the kernel command line via the
2572 retbleed=stuff option. For non-affected systems the overhead of this
2573 option is marginal as the call depth tracking is using run-time
2574 generated call thunks in a compiler generated padding area and call
2575 patching. This increases text size by ~5%. For non affected systems
2576 this space is unused. On affected SKL systems this results in a
2577 significant performance gain over the IBRS mitigation.
2578
2579config CALL_THUNKS_DEBUG
2580 bool "Enable call thunks and call depth tracking debugging"
2581 depends on MITIGATION_CALL_DEPTH_TRACKING
2582 select FUNCTION_ALIGNMENT_32B
2583 default n
2584 help
2585 Enable call/ret counters for imbalance detection and build in
2586 a noisy dmesg about callthunks generation and call patching for
2587 trouble shooting. The debug prints need to be enabled on the
2588 kernel command line with 'debug-callthunks'.
2589 Only enable this when you are debugging call thunks as this
2590 creates a noticeable runtime overhead. If unsure say N.
2591
2592config MITIGATION_IBPB_ENTRY
2593 bool "Enable IBPB on kernel entry"
2594 depends on CPU_SUP_AMD && X86_64
2595 default y
2596 help
2597 Compile the kernel with support for the retbleed=ibpb and
2598 spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations.
2599
2600config MITIGATION_IBRS_ENTRY
2601 bool "Enable IBRS on kernel entry"
2602 depends on CPU_SUP_INTEL && X86_64
2603 default y
2604 help
2605 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2606 This mitigates both spectre_v2 and retbleed at great cost to
2607 performance.
2608
2609config MITIGATION_SRSO
2610 bool "Mitigate speculative RAS overflow on AMD"
2611 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK
2612 default y
2613 help
2614 Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2615
2616config MITIGATION_SLS
2617 bool "Mitigate Straight-Line-Speculation"
2618 depends on CC_HAS_SLS && X86_64
2619 select OBJTOOL if HAVE_OBJTOOL
2620 default n
2621 help
2622 Compile the kernel with straight-line-speculation options to guard
2623 against straight line speculation. The kernel image might be slightly
2624 larger.
2625
2626config MITIGATION_GDS
2627 bool "Mitigate Gather Data Sampling"
2628 depends on CPU_SUP_INTEL
2629 default y
2630 help
2631 Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware
2632 vulnerability which allows unprivileged speculative access to data
2633 which was previously stored in vector registers. The attacker uses gather
2634 instructions to infer the stale vector register data.
2635
2636config MITIGATION_RFDS
2637 bool "RFDS Mitigation"
2638 depends on CPU_SUP_INTEL
2639 default y
2640 help
2641 Enable mitigation for Register File Data Sampling (RFDS) by default.
2642 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It
2643 allows unprivileged speculative access to stale data previously
2644 stored in floating point, vector and integer registers.
2645 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst>
2646
2647config MITIGATION_SPECTRE_BHI
2648 bool "Mitigate Spectre-BHB (Branch History Injection)"
2649 depends on CPU_SUP_INTEL
2650 default y
2651 help
2652 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks
2653 where the branch history buffer is poisoned to speculatively steer
2654 indirect branches.
2655 See <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2656
2657config MITIGATION_MDS
2658 bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug"
2659 depends on CPU_SUP_INTEL
2660 default y
2661 help
2662 Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is
2663 a hardware vulnerability which allows unprivileged speculative access
2664 to data which is available in various CPU internal buffers.
2665 See also <file:Documentation/admin-guide/hw-vuln/mds.rst>
2666
2667config MITIGATION_TAA
2668 bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug"
2669 depends on CPU_SUP_INTEL
2670 default y
2671 help
2672 Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware
2673 vulnerability that allows unprivileged speculative access to data
2674 which is available in various CPU internal buffers by using
2675 asynchronous aborts within an Intel TSX transactional region.
2676 See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst>
2677
2678config MITIGATION_MMIO_STALE_DATA
2679 bool "Mitigate MMIO Stale Data hardware bug"
2680 depends on CPU_SUP_INTEL
2681 default y
2682 help
2683 Enable mitigation for MMIO Stale Data hardware bugs. Processor MMIO
2684 Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO)
2685 vulnerabilities that can expose data. The vulnerabilities require the
2686 attacker to have access to MMIO.
2687 See also
2688 <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst>
2689
2690config MITIGATION_L1TF
2691 bool "Mitigate L1 Terminal Fault (L1TF) hardware bug"
2692 depends on CPU_SUP_INTEL
2693 default y
2694 help
2695 Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a
2696 hardware vulnerability which allows unprivileged speculative access to data
2697 available in the Level 1 Data Cache.
2698 See <file:Documentation/admin-guide/hw-vuln/l1tf.rst
2699
2700config MITIGATION_RETBLEED
2701 bool "Mitigate RETBleed hardware bug"
2702 depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY
2703 default y
2704 help
2705 Enable mitigation for RETBleed (Arbitrary Speculative Code Execution
2706 with Return Instructions) vulnerability. RETBleed is a speculative
2707 execution attack which takes advantage of microarchitectural behavior
2708 in many modern microprocessors, similar to Spectre v2. An
2709 unprivileged attacker can use these flaws to bypass conventional
2710 memory security restrictions to gain read access to privileged memory
2711 that would otherwise be inaccessible.
2712
2713config MITIGATION_SPECTRE_V1
2714 bool "Mitigate SPECTRE V1 hardware bug"
2715 default y
2716 help
2717 Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a
2718 class of side channel attacks that takes advantage of speculative
2719 execution that bypasses conditional branch instructions used for
2720 memory access bounds check.
2721 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2722
2723config MITIGATION_SPECTRE_V2
2724 bool "Mitigate SPECTRE V2 hardware bug"
2725 default y
2726 help
2727 Enable mitigation for Spectre V2 (Branch Target Injection). Spectre
2728 V2 is a class of side channel attacks that takes advantage of
2729 indirect branch predictors inside the processor. In Spectre variant 2
2730 attacks, the attacker can steer speculative indirect branches in the
2731 victim to gadget code by poisoning the branch target buffer of a CPU
2732 used for predicting indirect branch addresses.
2733 See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2734
2735config MITIGATION_SRBDS
2736 bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug"
2737 depends on CPU_SUP_INTEL
2738 default y
2739 help
2740 Enable mitigation for Special Register Buffer Data Sampling (SRBDS).
2741 SRBDS is a hardware vulnerability that allows Microarchitectural Data
2742 Sampling (MDS) techniques to infer values returned from special
2743 register accesses. An unprivileged user can extract values returned
2744 from RDRAND and RDSEED executed on another core or sibling thread
2745 using MDS techniques.
2746 See also
2747 <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst>
2748
2749config MITIGATION_SSB
2750 bool "Mitigate Speculative Store Bypass (SSB) hardware bug"
2751 default y
2752 help
2753 Enable mitigation for Speculative Store Bypass (SSB). SSB is a
2754 hardware security vulnerability and its exploitation takes advantage
2755 of speculative execution in a similar way to the Meltdown and Spectre
2756 security vulnerabilities.
2757
2758endif
2759
2760config ARCH_HAS_ADD_PAGES
2761 def_bool y
2762 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2763
2764menu "Power management and ACPI options"
2765
2766config ARCH_HIBERNATION_HEADER
2767 def_bool y
2768 depends on HIBERNATION
2769
2770source "kernel/power/Kconfig"
2771
2772source "drivers/acpi/Kconfig"
2773
2774config X86_APM_BOOT
2775 def_bool y
2776 depends on APM
2777
2778menuconfig APM
2779 tristate "APM (Advanced Power Management) BIOS support"
2780 depends on X86_32 && PM_SLEEP
2781 help
2782 APM is a BIOS specification for saving power using several different
2783 techniques. This is mostly useful for battery powered laptops with
2784 APM compliant BIOSes. If you say Y here, the system time will be
2785 reset after a RESUME operation, the /proc/apm device will provide
2786 battery status information, and user-space programs will receive
2787 notification of APM "events" (e.g. battery status change).
2788
2789 If you select "Y" here, you can disable actual use of the APM
2790 BIOS by passing the "apm=off" option to the kernel at boot time.
2791
2792 Note that the APM support is almost completely disabled for
2793 machines with more than one CPU.
2794
2795 In order to use APM, you will need supporting software. For location
2796 and more information, read <file:Documentation/power/apm-acpi.rst>
2797 and the Battery Powered Linux mini-HOWTO, available from
2798 <http://www.tldp.org/docs.html#howto>.
2799
2800 This driver does not spin down disk drives (see the hdparm(8)
2801 manpage ("man 8 hdparm") for that), and it doesn't turn off
2802 VESA-compliant "green" monitors.
2803
2804 This driver does not support the TI 4000M TravelMate and the ACER
2805 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2806 desktop machines also don't have compliant BIOSes, and this driver
2807 may cause those machines to panic during the boot phase.
2808
2809 Generally, if you don't have a battery in your machine, there isn't
2810 much point in using this driver and you should say N. If you get
2811 random kernel OOPSes or reboots that don't seem to be related to
2812 anything, try disabling/enabling this option (or disabling/enabling
2813 APM in your BIOS).
2814
2815 Some other things you should try when experiencing seemingly random,
2816 "weird" problems:
2817
2818 1) make sure that you have enough swap space and that it is
2819 enabled.
2820 2) pass the "idle=poll" option to the kernel
2821 3) switch on floating point emulation in the kernel and pass
2822 the "no387" option to the kernel
2823 4) pass the "floppy=nodma" option to the kernel
2824 5) pass the "mem=4M" option to the kernel (thereby disabling
2825 all but the first 4 MB of RAM)
2826 6) make sure that the CPU is not over clocked.
2827 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2828 8) disable the cache from your BIOS settings
2829 9) install a fan for the video card or exchange video RAM
2830 10) install a better fan for the CPU
2831 11) exchange RAM chips
2832 12) exchange the motherboard.
2833
2834 To compile this driver as a module, choose M here: the
2835 module will be called apm.
2836
2837if APM
2838
2839config APM_IGNORE_USER_SUSPEND
2840 bool "Ignore USER SUSPEND"
2841 help
2842 This option will ignore USER SUSPEND requests. On machines with a
2843 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2844 series notebooks, it is necessary to say Y because of a BIOS bug.
2845
2846config APM_DO_ENABLE
2847 bool "Enable PM at boot time"
2848 help
2849 Enable APM features at boot time. From page 36 of the APM BIOS
2850 specification: "When disabled, the APM BIOS does not automatically
2851 power manage devices, enter the Standby State, enter the Suspend
2852 State, or take power saving steps in response to CPU Idle calls."
2853 This driver will make CPU Idle calls when Linux is idle (unless this
2854 feature is turned off -- see "Do CPU IDLE calls", below). This
2855 should always save battery power, but more complicated APM features
2856 will be dependent on your BIOS implementation. You may need to turn
2857 this option off if your computer hangs at boot time when using APM
2858 support, or if it beeps continuously instead of suspending. Turn
2859 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2860 T400CDT. This is off by default since most machines do fine without
2861 this feature.
2862
2863config APM_CPU_IDLE
2864 depends on CPU_IDLE
2865 bool "Make CPU Idle calls when idle"
2866 help
2867 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2868 On some machines, this can activate improved power savings, such as
2869 a slowed CPU clock rate, when the machine is idle. These idle calls
2870 are made after the idle loop has run for some length of time (e.g.,
2871 333 mS). On some machines, this will cause a hang at boot time or
2872 whenever the CPU becomes idle. (On machines with more than one CPU,
2873 this option does nothing.)
2874
2875config APM_DISPLAY_BLANK
2876 bool "Enable console blanking using APM"
2877 help
2878 Enable console blanking using the APM. Some laptops can use this to
2879 turn off the LCD backlight when the screen blanker of the Linux
2880 virtual console blanks the screen. Note that this is only used by
2881 the virtual console screen blanker, and won't turn off the backlight
2882 when using the X Window system. This also doesn't have anything to
2883 do with your VESA-compliant power-saving monitor. Further, this
2884 option doesn't work for all laptops -- it might not turn off your
2885 backlight at all, or it might print a lot of errors to the console,
2886 especially if you are using gpm.
2887
2888config APM_ALLOW_INTS
2889 bool "Allow interrupts during APM BIOS calls"
2890 help
2891 Normally we disable external interrupts while we are making calls to
2892 the APM BIOS as a measure to lessen the effects of a badly behaving
2893 BIOS implementation. The BIOS should reenable interrupts if it
2894 needs to. Unfortunately, some BIOSes do not -- especially those in
2895 many of the newer IBM Thinkpads. If you experience hangs when you
2896 suspend, try setting this to Y. Otherwise, say N.
2897
2898endif # APM
2899
2900source "drivers/cpufreq/Kconfig"
2901
2902source "drivers/cpuidle/Kconfig"
2903
2904source "drivers/idle/Kconfig"
2905
2906endmenu
2907
2908menu "Bus options (PCI etc.)"
2909
2910choice
2911 prompt "PCI access mode"
2912 depends on X86_32 && PCI
2913 default PCI_GOANY
2914 help
2915 On PCI systems, the BIOS can be used to detect the PCI devices and
2916 determine their configuration. However, some old PCI motherboards
2917 have BIOS bugs and may crash if this is done. Also, some embedded
2918 PCI-based systems don't have any BIOS at all. Linux can also try to
2919 detect the PCI hardware directly without using the BIOS.
2920
2921 With this option, you can specify how Linux should detect the
2922 PCI devices. If you choose "BIOS", the BIOS will be used,
2923 if you choose "Direct", the BIOS won't be used, and if you
2924 choose "MMConfig", then PCI Express MMCONFIG will be used.
2925 If you choose "Any", the kernel will try MMCONFIG, then the
2926 direct access method and falls back to the BIOS if that doesn't
2927 work. If unsure, go with the default, which is "Any".
2928
2929config PCI_GOBIOS
2930 bool "BIOS"
2931
2932config PCI_GOMMCONFIG
2933 bool "MMConfig"
2934
2935config PCI_GODIRECT
2936 bool "Direct"
2937
2938config PCI_GOOLPC
2939 bool "OLPC XO-1"
2940 depends on OLPC
2941
2942config PCI_GOANY
2943 bool "Any"
2944
2945endchoice
2946
2947config PCI_BIOS
2948 def_bool y
2949 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2950
2951# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2952config PCI_DIRECT
2953 def_bool y
2954 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2955
2956config PCI_MMCONFIG
2957 bool "Support mmconfig PCI config space access" if X86_64
2958 default y
2959 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2960 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2961
2962config PCI_OLPC
2963 def_bool y
2964 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2965
2966config PCI_XEN
2967 def_bool y
2968 depends on PCI && XEN
2969
2970config MMCONF_FAM10H
2971 def_bool y
2972 depends on X86_64 && PCI_MMCONFIG && ACPI
2973
2974config PCI_CNB20LE_QUIRK
2975 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2976 depends on PCI
2977 help
2978 Read the PCI windows out of the CNB20LE host bridge. This allows
2979 PCI hotplug to work on systems with the CNB20LE chipset which do
2980 not have ACPI.
2981
2982 There's no public spec for this chipset, and this functionality
2983 is known to be incomplete.
2984
2985 You should say N unless you know you need this.
2986
2987config ISA_BUS
2988 bool "ISA bus support on modern systems" if EXPERT
2989 help
2990 Expose ISA bus device drivers and options available for selection and
2991 configuration. Enable this option if your target machine has an ISA
2992 bus. ISA is an older system, displaced by PCI and newer bus
2993 architectures -- if your target machine is modern, it probably does
2994 not have an ISA bus.
2995
2996 If unsure, say N.
2997
2998# x86_64 have no ISA slots, but can have ISA-style DMA.
2999config ISA_DMA_API
3000 bool "ISA-style DMA support" if (X86_64 && EXPERT)
3001 default y
3002 help
3003 Enables ISA-style DMA support for devices requiring such controllers.
3004 If unsure, say Y.
3005
3006if X86_32
3007
3008config ISA
3009 bool "ISA support"
3010 help
3011 Find out whether you have ISA slots on your motherboard. ISA is the
3012 name of a bus system, i.e. the way the CPU talks to the other stuff
3013 inside your box. Other bus systems are PCI, EISA, MicroChannel
3014 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
3015 newer boards don't support it. If you have ISA, say Y, otherwise N.
3016
3017config SCx200
3018 tristate "NatSemi SCx200 support"
3019 help
3020 This provides basic support for National Semiconductor's
3021 (now AMD's) Geode processors. The driver probes for the
3022 PCI-IDs of several on-chip devices, so its a good dependency
3023 for other scx200_* drivers.
3024
3025 If compiled as a module, the driver is named scx200.
3026
3027config SCx200HR_TIMER
3028 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
3029 depends on SCx200
3030 default y
3031 help
3032 This driver provides a clocksource built upon the on-chip
3033 27MHz high-resolution timer. Its also a workaround for
3034 NSC Geode SC-1100's buggy TSC, which loses time when the
3035 processor goes idle (as is done by the scheduler). The
3036 other workaround is idle=poll boot option.
3037
3038config OLPC
3039 bool "One Laptop Per Child support"
3040 depends on !X86_PAE
3041 select GPIOLIB
3042 select OF
3043 select OF_PROMTREE
3044 select IRQ_DOMAIN
3045 select OLPC_EC
3046 help
3047 Add support for detecting the unique features of the OLPC
3048 XO hardware.
3049
3050config OLPC_XO1_PM
3051 bool "OLPC XO-1 Power Management"
3052 depends on OLPC && MFD_CS5535=y && PM_SLEEP
3053 help
3054 Add support for poweroff and suspend of the OLPC XO-1 laptop.
3055
3056config OLPC_XO1_RTC
3057 bool "OLPC XO-1 Real Time Clock"
3058 depends on OLPC_XO1_PM && RTC_DRV_CMOS
3059 help
3060 Add support for the XO-1 real time clock, which can be used as a
3061 programmable wakeup source.
3062
3063config OLPC_XO1_SCI
3064 bool "OLPC XO-1 SCI extras"
3065 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
3066 depends on INPUT=y
3067 select POWER_SUPPLY
3068 help
3069 Add support for SCI-based features of the OLPC XO-1 laptop:
3070 - EC-driven system wakeups
3071 - Power button
3072 - Ebook switch
3073 - Lid switch
3074 - AC adapter status updates
3075 - Battery status updates
3076
3077config OLPC_XO15_SCI
3078 bool "OLPC XO-1.5 SCI extras"
3079 depends on OLPC && ACPI
3080 select POWER_SUPPLY
3081 help
3082 Add support for SCI-based features of the OLPC XO-1.5 laptop:
3083 - EC-driven system wakeups
3084 - AC adapter status updates
3085 - Battery status updates
3086
3087config GEODE_COMMON
3088 bool
3089
3090config ALIX
3091 bool "PCEngines ALIX System Support (LED setup)"
3092 select GPIOLIB
3093 select GEODE_COMMON
3094 help
3095 This option enables system support for the PCEngines ALIX.
3096 At present this just sets up LEDs for GPIO control on
3097 ALIX2/3/6 boards. However, other system specific setup should
3098 get added here.
3099
3100 Note: You must still enable the drivers for GPIO and LED support
3101 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
3102
3103 Note: You have to set alix.force=1 for boards with Award BIOS.
3104
3105config NET5501
3106 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
3107 select GPIOLIB
3108 select GEODE_COMMON
3109 help
3110 This option enables system support for the Soekris Engineering net5501.
3111
3112config GEOS
3113 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
3114 select GPIOLIB
3115 select GEODE_COMMON
3116 depends on DMI
3117 help
3118 This option enables system support for the Traverse Technologies GEOS.
3119
3120config TS5500
3121 bool "Technologic Systems TS-5500 platform support"
3122 depends on MELAN
3123 select CHECK_SIGNATURE
3124 select NEW_LEDS
3125 select LEDS_CLASS
3126 help
3127 This option enables system support for the Technologic Systems TS-5500.
3128
3129endif # X86_32
3130
3131config AMD_NB
3132 def_bool y
3133 depends on CPU_SUP_AMD && PCI
3134
3135endmenu
3136
3137menu "Binary Emulations"
3138
3139config IA32_EMULATION
3140 bool "IA32 Emulation"
3141 depends on X86_64
3142 select ARCH_WANT_OLD_COMPAT_IPC
3143 select BINFMT_ELF
3144 select COMPAT_OLD_SIGACTION
3145 help
3146 Include code to run legacy 32-bit programs under a
3147 64-bit kernel. You should likely turn this on, unless you're
3148 100% sure that you don't have any 32-bit programs left.
3149
3150config IA32_EMULATION_DEFAULT_DISABLED
3151 bool "IA32 emulation disabled by default"
3152 default n
3153 depends on IA32_EMULATION
3154 help
3155 Make IA32 emulation disabled by default. This prevents loading 32-bit
3156 processes and access to 32-bit syscalls. If unsure, leave it to its
3157 default value.
3158
3159config X86_X32_ABI
3160 bool "x32 ABI for 64-bit mode"
3161 depends on X86_64
3162 # llvm-objcopy does not convert x86_64 .note.gnu.property or
3163 # compressed debug sections to x86_x32 properly:
3164 # https://github.com/ClangBuiltLinux/linux/issues/514
3165 # https://github.com/ClangBuiltLinux/linux/issues/1141
3166 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3167 help
3168 Include code to run binaries for the x32 native 32-bit ABI
3169 for 64-bit processors. An x32 process gets access to the
3170 full 64-bit register file and wide data path while leaving
3171 pointers at 32 bits for smaller memory footprint.
3172
3173config COMPAT_32
3174 def_bool y
3175 depends on IA32_EMULATION || X86_32
3176 select HAVE_UID16
3177 select OLD_SIGSUSPEND3
3178
3179config COMPAT
3180 def_bool y
3181 depends on IA32_EMULATION || X86_X32_ABI
3182
3183config COMPAT_FOR_U64_ALIGNMENT
3184 def_bool y
3185 depends on COMPAT
3186
3187endmenu
3188
3189config HAVE_ATOMIC_IOMAP
3190 def_bool y
3191 depends on X86_32
3192
3193source "arch/x86/kvm/Kconfig"
3194
3195source "arch/x86/Kconfig.assembler"